diff --git a/ethereumj-core/src/main/java/org/ethereum/config/SystemProperties.java b/ethereumj-core/src/main/java/org/ethereum/config/SystemProperties.java
index 49084588..f9133d1f 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/SystemProperties.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/SystemProperties.java
@@ -19,13 +19,20 @@ public class SystemProperties {
 
 	private static Logger logger = LoggerFactory.getLogger(SystemProperties.class);
 	
+	private static int DEFAULT_TX_APPROVE_TIMEOUT = 10;
+	private static String DEFAULT_DISCOVERY_PEER = "54.201.28.117";
+	private static int DEFAULT_DISCOVERY_PORT = 30303;
+	private static String DEFAULT_ACTIVE_PEER_IP = "54.201.28.117";
+	private static int DEFAULT_ACTIVE_PORT = 30303;
+	private static String DEFAULT_SAMPLES_DIR = "samples";
+	
 	public static SystemProperties CONFIG = new SystemProperties();
     private Properties prop = new Properties();
     private InputStream input = null;
     
     public SystemProperties() {
-        try {
-
+        
+    	try {
             File file = null;
             String dir = System.getProperty("user.dir");
             String fileName = dir + "/config/system.properties";
@@ -41,7 +48,6 @@ public class SystemProperties {
                     return;
                 }
             }
-
             //load a properties file from class path, inside static method
             prop.load(input);
 
@@ -77,18 +83,17 @@ public class SystemProperties {
 
     public int transactionApproveTimeout(){
         if (prop.isEmpty())
-            return 10;
+            return DEFAULT_TX_APPROVE_TIMEOUT;
         return Integer.parseInt(prop.getProperty("transaction.approve.timeout"));
     }
 
-
     public String peerDiscoveryIP(){
-        if(prop.isEmpty()) return "54.201.28.117";
+        if(prop.isEmpty()) return DEFAULT_DISCOVERY_PEER;
         return prop.getProperty("peer.discovery.ip");
     }
 
     public int peerDiscoveryPort(){
-        if(prop.isEmpty()) return 30303;
+        if(prop.isEmpty()) return DEFAULT_DISCOVERY_PORT;
         return Integer.parseInt(prop.getProperty("peer.discovery.port"));
     }
     
@@ -98,21 +103,21 @@ public class SystemProperties {
     }
 
     public String activePeerIP(){
-        if(prop.isEmpty()) return "54.201.28.117";
+        if(prop.isEmpty()) return DEFAULT_ACTIVE_PEER_IP;
         return prop.getProperty("peer.active.ip");
     }
 
     public int activePeerPort(){
-        if(prop.isEmpty()) return 30303;
+        if(prop.isEmpty()) return DEFAULT_ACTIVE_PORT;
         return Integer.parseInt(prop.getProperty("peer.active.port"));
     }
 
     public String samplesDir(){
-        if(prop.isEmpty()) return "samples";
+        if(prop.isEmpty()) return DEFAULT_SAMPLES_DIR;
         return prop.getProperty("samples.dir");
     }
 
-	public String toString() {
+	public void print() {
 		Enumeration<?> e = prop.propertyNames();
 		while (e.hasMoreElements()) {
 			String key = (String) e.nextElement();
@@ -120,11 +125,10 @@ public class SystemProperties {
 			if (!key.equals("null"))
 				logger.info("Key: " + key + ", Value: " + value);
 		}
-		return "";
 	}
 
     public static void main(String args[]){
         SystemProperties systemProperties = new SystemProperties();
-        logger.info(systemProperties.toString());
+        systemProperties.print();
     }
 }
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/AccountState.java b/ethereumj-core/src/main/java/org/ethereum/core/AccountState.java
index 1c984a5b..5a45814a 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/AccountState.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/AccountState.java
@@ -27,7 +27,7 @@ public class AccountState {
      * 
      * Since I typically wish to refer not to the trie’s root hash 
      * but to the underlying set of key/value pairs stored within, 
-     * I define a convenient equi valence TRIE (σ[a] s ) ≡ σ[a] s . 
+     * I define a convenient equivalence TRIE (σ[a] s ) ≡ σ[a] s . 
      * It shall be understood that σ[a] s is not a ‘physical’ member 
      * of the account and does not contribute to its later serialisation */
     private byte[] stateRoot = new byte[0];
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/Blockchain.java b/ethereumj-core/src/main/java/org/ethereum/core/Blockchain.java
index b7549ba1..2c08d939 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/Blockchain.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/Blockchain.java
@@ -1,7 +1,6 @@
 package org.ethereum.core;
 
 import java.io.IOException;
-import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -20,31 +19,22 @@ import org.spongycastle.util.encoders.Hex;
 
 public class Blockchain extends ArrayList<Block> {
 
+	private static final long serialVersionUID = -143590724563460486L;
+
 	private static Logger logger = LoggerFactory.getLogger(Blockchain.class);
 	
 	private Database db;
 	private Wallet wallet;
     private long gasPrice = 1000;
-    private Block lastBlock = new Genesis();
+    private Block lastBlock;
 
-    private Map<BigInteger, PendingTransaction> pendingTransactions =
-            Collections.synchronizedMap(new HashMap<BigInteger, PendingTransaction>());
+    private Map<String, PendingTransaction> pendingTransactions =
+            Collections.synchronizedMap(new HashMap<String, PendingTransaction>());
 	
 	public Blockchain(Wallet wallet) {
 		this.db = Config.CHAIN_DB;
 		this.wallet = wallet;
-		
-        // Redesign fetch all to get the chain ordered
-        byte[] payload = db.get(Genesis.PARENT_HASH);
-
-        while (payload != null) {
-
-            Block block = new Block(payload);
-            this.add(block);
-            lastBlock  = block;
-            wallet.processBlock(block);
-            payload = db.get(block.getHash());
-        }
+		this.loadChain();
 	}
 
 	public Block getLastBlock() {
@@ -55,59 +45,65 @@ public class Blockchain extends ArrayList<Block> {
 
         // TODO: redesign this part when the state part and the genesis block is ready
 
-        if (blocks.isEmpty()) return;
+		if (blocks.isEmpty())
+			return;
 
         Block firstBlockToAdd = blocks.get(blocks.size() - 1);
 
         // if it is the first block to add
         // check that the parent is the genesis
-        if (this.isEmpty() &&
-            !Arrays.equals(StaticMessages.GENESIS_HASH, firstBlockToAdd.getParentHash())){
-             return;
-        }	
+		if (this.isEmpty()
+				&& !Arrays.equals(StaticMessages.GENESIS_HASH,
+						firstBlockToAdd.getParentHash())) {
+			return;
+		}
         // if there is some blocks already keep chain continuity
-        if (!this.isEmpty() ){
+        if (!this.isEmpty()) {
             Block lastBlock = this.get(this.size() - 1);
             String hashLast = Hex.toHexString(lastBlock.getHash());
             String blockParentHash = Hex.toHexString(firstBlockToAdd.getParentHash());
             if (!hashLast.equals(blockParentHash)) return;
         }
         for (int i = blocks.size() - 1; i >= 0 ; --i){
-            Block block = blocks.get(i);
-            this.add(block);
-            if(block.getNumber() > lastBlock.getNumber()) lastBlock = block;
-
+        	Block block = blocks.get(i);
+            this.addBlock(block);
             db.put(block.getParentHash(), block.getEncoded());
-
             if (logger.isDebugEnabled())
                 logger.debug("block added to the chain with hash: {}", Hex.toHexString(block.getHash()));
-            this.gasPrice = block.getMinGasPrice();
-
-            wallet.processBlock(block);
         }	
         // Remove all pending transactions as they already approved by the net
-        for (Block block : blocks){
-            for (Transaction tx : block.getTransactionsList()){
+        for (Block block : blocks) {
+            for (Transaction tx : block.getTransactionsList()) {
                 if (logger.isDebugEnabled())
                     logger.debug("pending cleanup: tx.hash: [{}]", Hex.toHexString( tx.getHash()));
                 removePendingTransaction(tx);
             }
         }
-
         logger.info("*** Block chain size: [ {} ]", this.size());
     }
     
-    /*
-     *        1) the dialog put a pending transaction on the list
-     *        2) the dialog send the transaction to a net
-     *        3) wherever the transaction got in from the wire it will change to approve state
-     *        4) only after the approve a) Wallet state changes
-     *        5) After the block is received with that tx the pending been clean up
-    */
+    private void addBlock(Block block) {
+		this.wallet.processBlock(block);
+        this.gasPrice = block.getMinGasPrice();
+		if(lastBlock == null || block.getNumber() > lastBlock.getNumber())
+			this.lastBlock = block;
+		this.add(block);
+    }
+    
+    public long getGasPrice() {
+        return gasPrice;
+    }
+    
+    /***********************************************************************
+     *	1) the dialog put a pending transaction on the list
+     *  2) the dialog send the transaction to a net
+     *  3) wherever the transaction got in from the wire it will change to approve state
+     *  4) only after the approve a) Wallet state changes
+     *  5) After the block is received with that tx the pending been clean up
+     */
     public PendingTransaction addPendingTransaction(Transaction transaction) {
-
-        BigInteger hash = new BigInteger(transaction.getHash());
-        logger.info("pending transaction placed hash: {} ", hash.toString(16) );
+        String hash = Hex.toHexString(transaction.getHash());
+        logger.info("pending transaction placed hash: {} ", hash );
 
         PendingTransaction pendingTransaction =  pendingTransactions.get(hash);
 		if (pendingTransaction != null)
@@ -120,24 +116,44 @@ public class Blockchain extends ArrayList<Block> {
     }
 
     public void removePendingTransaction(Transaction transaction){
-
-        BigInteger hash = new BigInteger(transaction.getHash());
-        logger.info("pending transaction removed with hash: {} ",  hash.toString(16) );
+        String hash = Hex.toHexString(transaction.getHash());
+        logger.info("pending transaction removed with hash: {} ",  hash );
         pendingTransactions.remove(hash);
     }
 
-    public long getGasPrice() {
-        return gasPrice;
-    }
-
     public byte[] getLatestBlockHash(){
-
-        if (this.isEmpty())
-            return StaticMessages.GENESIS_HASH;
-        else{
-
-            return lastBlock.getHash();
-        }
-
+		if (this.isEmpty())
+			return StaticMessages.GENESIS_HASH;
+		else
+			return lastBlock.getHash();
     }
+    
+	public void loadChain() {
+		DBIterator iterator = db.iterator();
+		try {
+			if (!iterator.hasNext()) {
+				logger.info("DB is empty - adding Genesis");
+				Block genesis = Genesis.getInstance();
+				this.addBlock(genesis);
+				logger.debug("Block: " + genesis.getNumber() + " ---> " + genesis.toFlatString());
+				db.put(genesis.getParentHash(), genesis.getEncoded());
+			} else {
+				logger.debug("Displaying blocks stored in DB sorted on blocknumber");
+				byte[] parentHash = Genesis.PARENT_HASH; // get Genesis block by parentHash
+				for (iterator.seekToFirst(); iterator.hasNext(); iterator.next()) {
+					this.addBlock(new Block(db.get(parentHash)));
+					if (logger.isDebugEnabled())
+						logger.debug("Block: " + lastBlock.getNumber() + " ---> " + lastBlock.toFlatString());
+					parentHash = lastBlock.getHash();					
+				}
+			}
+		} finally {
+			// Make sure you close the iterator to avoid resource leaks.
+			try {
+				iterator.close();
+			} catch (IOException e) {
+				logger.error(e.getMessage(), e);
+			}
+		}
+	}
 }
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/Genesis.java b/ethereumj-core/src/main/java/org/ethereum/core/Genesis.java
index 6e438297..b103f379 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/Genesis.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/Genesis.java
@@ -29,8 +29,10 @@ public class Genesis extends Block {
     public static long TIMESTAMP = 0;
     public static byte[] EXTRA_DATA = new byte[0];
     public static byte[] NONCE = HashUtil.sha3(new byte[]{42});
-			
-	public Genesis() {
+    
+    private static Block instance;
+    
+	private Genesis() {
 		super(PARENT_HASH, UNCLES_HASH, COINBASE, TX_TRIE_ROOT, DIFFICULTY,
 				NUMBER, MIN_GAS_PRICE, GAS_LIMIT, GAS_USED, TIMESTAMP,
 				EXTRA_DATA, NONCE, null, null);
@@ -53,9 +55,16 @@ public class Genesis extends Block {
 		this.updateState(Hex.decode("6c386a4b26f73c802f34673f7248bb118f97424a"), acct.getEncoded());
 		// # (R)
 		this.updateState(Hex.decode("cd2a3d9f938e13cd947ec05abc7fe734df8dd826"), acct.getEncoded());
-		System.out.println(Hex.toHexString(this.getStateRoot()));
 		logger.info("Genesis-hash: " + Hex.toHexString(this.getHash()));
+		logger.info("Genesis-stateRoot: " + Hex.toHexString(this.getStateRoot()));
 
         Config.CHAIN_DB.put(getParentHash(), getEncoded());
     }
+	
+	public static Block getInstance() {
+		if (instance == null) {
+			instance = new Genesis();
+		}
+		return instance;
+	}
 }
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/StateObject.java b/ethereumj-core/src/main/java/org/ethereum/core/StateObject.java
index aa0eca02..7162d61c 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/StateObject.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/StateObject.java
@@ -160,7 +160,7 @@ public class StateObject {
 	// Converts an transaction in to a state object
 	public static StateObject createContract(Transaction tx, GoState state) {
 		// Create contract if there's no recipient
-		if (tx.isContract()) {
+		if (tx.isContractCreation()) {
 			// FIXME
 			byte[] txHash = tx.getHash();
 			byte[] contractAddress = copyOfRange(txHash, 12, txHash.length);
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java b/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
index 65db0692..db482d26 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
@@ -164,14 +164,14 @@ public class Transaction {
 
     public byte[] getContractAddress(){
 
-        if (!isContract()) return null;
+        if (!isContractCreation()) return null;
 
         byte[] encSender = RLP.encodeElement(getSender());
         byte[] encNonce = RLP.encodeElement(nonce);
         return HashUtil.sha3omit12(RLP.encodeList(encSender, encNonce));
     }
 
-    public boolean isContract() {
+    public boolean isContractCreation() {
         return Arrays.equals(this.receiveAddress, ZERO_ADDRESS);
     }
 
diff --git a/ethereumj-core/src/main/java/org/ethereum/crypto/ECKey.java b/ethereumj-core/src/main/java/org/ethereum/crypto/ECKey.java
index 20d9dfa7..e5a8870f 100644
--- a/ethereumj-core/src/main/java/org/ethereum/crypto/ECKey.java
+++ b/ethereumj-core/src/main/java/org/ethereum/crypto/ECKey.java
@@ -47,7 +47,7 @@ import org.spongycastle.util.encoders.Base64;
 import org.spongycastle.util.encoders.Hex;
  
 public class ECKey implements Serializable {
-	private static final Logger log = LoggerFactory.getLogger(ECKey.class);
+	private static final Logger logger = LoggerFactory.getLogger(ECKey.class);
 	
     /** The parameters of the secp256k1 curve that Bitcoin uses. */
     public static final ECDomainParameters CURVE;
@@ -448,11 +448,10 @@ public class ECKey implements Serializable {
         signer.init(false, params);
         try {
             return signer.verifySignature(data, signature.r, signature.s);
-        } catch (NullPointerException e) {
-            // Bouncy Castle contains a bug that can cause NPEs given specially crafted signatures. Those signatures
-            // are inherently invalid/attack sigs so we just fail them here rather than crash the thread.
-            log.error("Caught NPE inside bouncy castle");
-            e.printStackTrace();
+        } catch (NullPointerException npe) {
+            // Bouncy Castle contains a bug that can cause NPEs given specially crafted signatures. 
+        	// Those signatures are inherently invalid/attack sigs so we just fail them here rather than crash the thread.
+            logger.error("Caught NPE inside bouncy castle", npe);
             return false;
         }
     }
diff --git a/ethereumj-core/src/main/java/org/ethereum/db/Database.java b/ethereumj-core/src/main/java/org/ethereum/db/Database.java
index ba8c0edf..78e61c28 100644
--- a/ethereumj-core/src/main/java/org/ethereum/db/Database.java
+++ b/ethereumj-core/src/main/java/org/ethereum/db/Database.java
@@ -4,19 +4,13 @@ import static org.iq80.leveldb.impl.Iq80DBFactory.factory;
 
 import java.io.File;
 import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
 
 import org.ethereum.config.SystemProperties;
-import org.ethereum.core.Block;
-import org.ethereum.core.Genesis;
-import org.ethereum.net.message.StaticMessages;
 import org.iq80.leveldb.DB;
 import org.iq80.leveldb.DBIterator;
 import org.iq80.leveldb.Options;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import org.spongycastle.util.encoders.Hex;
 
 /**
  *  Generic interface for Ethereum database
@@ -47,8 +41,6 @@ public class Database {
 			logger.debug("Initializing new or existing DB: '" + name + "'");
 			options.createIfMissing(true);
 			db = factory.open(new File(name), options);
-
-			printDB();
 //			logger.debug("Showing database stats");
 //			String stats = DATABASE.getProperty("leveldb.stats");
 //			logger.debug(stats);
@@ -68,34 +60,6 @@ public class Database {
 		}
 	}
 	
-	public void printDB() {
-		DBIterator iterator = db.iterator();
-		try {
-			Map<Long, Block> blocks = new HashMap<Long, Block>();
-			int count = 0;
-			if (!iterator.hasNext()) {
-				logger.info("DB is empty");
-			} else {
-				logger.info("Displaying blocks stored in DB sorted on key");
-			}
-			for (iterator.seekToFirst(); iterator.hasNext(); iterator.next()) {
-				byte[] key = iterator.peekNext().getKey();
-				byte[] value = iterator.peekNext().getValue();
-				Block block = new Block(value);
-				blocks.put(new Long(block.getNumber()), block);
-				logger.info("Block: " + count + " Key: " + Hex.toHexString(key) + " ---> " + block.toFlatString());
-				count++;
-			}
-		} finally {
-			// Make sure you close the iterator to avoid resource leaks.
-			try {
-				iterator.close();
-			} catch (IOException e) {
-				e.printStackTrace();
-			}
-		}
-	}
-
 	/** Insert object(value) (key = sha3(value)) */
 	public void put(byte[] key, byte[] value) {
 		db.put(key, value);
diff --git a/ethereumj-core/src/main/java/org/ethereum/db/IpGeoDB.java b/ethereumj-core/src/main/java/org/ethereum/db/IpGeoDB.java
index 0fc1ac10..16dc28d4 100644
--- a/ethereumj-core/src/main/java/org/ethereum/db/IpGeoDB.java
+++ b/ethereumj-core/src/main/java/org/ethereum/db/IpGeoDB.java
@@ -4,6 +4,9 @@ import java.io.File;
 import java.net.InetAddress;
 import java.net.URL;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import com.maxmind.geoip.Location;
 import com.maxmind.geoip.LookupService;
 
@@ -14,27 +17,30 @@ import com.maxmind.geoip.LookupService;
  */
 public class IpGeoDB {   // change
 
-    static{
-        try {
-            File file = null;
-            try {
+	private static Logger logger = LoggerFactory.getLogger(IpGeoDB.class);
+	
+	static {
+		try {
+			File file = null;
+			try {
 
-                String dir = System.getProperty("user.dir");
-                String fileName = dir + "/config/GeoLiteCity.dat";
-                file = new File(fileName);
-                if (!file.exists()){
-                    URL geiIpDBFile = ClassLoader.getSystemResource("GeoLiteCity.dat");
-                    file = new File(geiIpDBFile.toURI());
-                }
-            } catch (Throwable th) {
-                th.printStackTrace();
-                System.exit(-1);
-            }
-            cl = new LookupService(file);
-        } catch (Throwable e) {
-            e.printStackTrace();
-        }
-    }
+				String dir = System.getProperty("user.dir");
+				String fileName = dir + "/config/GeoLiteCity.dat";
+				file = new File(fileName);
+				if (!file.exists()) {
+					URL geiIpDBFile = ClassLoader
+							.getSystemResource("GeoLiteCity.dat");
+					file = new File(geiIpDBFile.toURI());
+				}
+			} catch (Throwable th) {
+				logger.error(th.getMessage(), th);
+				System.exit(-1);
+			}
+			cl = new LookupService(file);
+		} catch (Throwable e) {
+			logger.error(e.getMessage(), e);
+		}
+	}
 
     private static LookupService cl;
 
@@ -42,9 +48,8 @@ public class IpGeoDB {   // change
         try {
             return cl.getLocation(ip);
         } catch (Throwable e) {
-            // todo: think about this exception, maybe you can do something more reasonable
-            System.out.println(e.getMessage());
-//            e.printStackTrace();
+            // TODO: think about this exception, maybe you can do something more reasonable
+        	logger.error(e.getMessage(), e);
         }
         return null;
     }
diff --git a/ethereumj-core/src/main/java/org/ethereum/gui/ContractSubmitDialog.java b/ethereumj-core/src/main/java/org/ethereum/gui/ContractSubmitDialog.java
index cf655044..d9c9dde0 100644
--- a/ethereumj-core/src/main/java/org/ethereum/gui/ContractSubmitDialog.java
+++ b/ethereumj-core/src/main/java/org/ethereum/gui/ContractSubmitDialog.java
@@ -22,17 +22,16 @@ import java.math.BigInteger;
 import java.net.URL;
 import java.util.Collection;
 
-
-
 /**
  * www.ethereumJ.com
  * User: Roman Mandeleil
  * Created on: 18/05/14 22:21
  */
-class ContractSubmitDialog extends JDialog implements MessageAwareDialog{
+class ContractSubmitDialog extends JDialog implements MessageAwareDialog {
 
-
-    ContractSubmitDialog dialog;
+    private static final long serialVersionUID = -3622984456084608996L;
+	
+	ContractSubmitDialog dialog;
     JComboBox<AddressStateWraper> creatorAddressCombo;
     final JTextField gasInput;
     final JTextField contractAddrInput;
@@ -101,7 +100,6 @@ class ContractSubmitDialog extends JDialog implements MessageAwareDialog{
                     }}
         );
 
-
         JLabel statusMessage = new JLabel("");
         statusMessage.setBounds(50, 360, 400, 50);
         statusMessage.setHorizontalAlignment(SwingConstants.CENTER);
@@ -291,8 +289,6 @@ class ContractSubmitDialog extends JDialog implements MessageAwareDialog{
 
     }
 
-
-
     public static void main(String args[]) {
 
         AccountState as = new AccountState();
@@ -319,8 +315,7 @@ class ContractSubmitDialog extends JDialog implements MessageAwareDialog{
             String valueShort   = Utils.getValueShortString(addressState.getBalance());
 
             String result =
-                    String.format(" By: [%s] %s",
-                            addressShort, valueShort);
+                    String.format(" By: [%s] %s", addressShort, valueShort);
 
             return result;
         }
diff --git a/ethereumj-core/src/main/java/org/ethereum/gui/DialogWorker.java b/ethereumj-core/src/main/java/org/ethereum/gui/DialogWorker.java
index f0f8907e..53275532 100644
--- a/ethereumj-core/src/main/java/org/ethereum/gui/DialogWorker.java
+++ b/ethereumj-core/src/main/java/org/ethereum/gui/DialogWorker.java
@@ -4,8 +4,11 @@ import org.ethereum.core.Transaction;
 import org.ethereum.manager.MainData;
 import org.ethereum.net.submit.TransactionExecutor;
 import org.ethereum.net.submit.TransactionTask;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.swing.*;
+
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
@@ -18,13 +21,14 @@ import static org.ethereum.config.SystemProperties.CONFIG;
  * User: Roman Mandeleil
  * Created on: 26/05/2014 12:27
  */
-
 public class DialogWorker extends SwingWorker {
 
-    Transaction tx;
-    MessageAwareDialog dialog;
+	private static Logger logger = LoggerFactory.getLogger(DialogWorker.class);
+	
+    private Transaction tx;
+    private MessageAwareDialog dialog;
 
-    DialogWorker(Transaction tx, MessageAwareDialog dialog) {
+    public DialogWorker(Transaction tx, MessageAwareDialog dialog) {
         this.tx = tx;
         this.dialog = dialog;
     }
@@ -32,21 +36,21 @@ public class DialogWorker extends SwingWorker {
     @Override
     protected Object doInBackground() throws Exception {
         TransactionTask transactionTask = new TransactionTask(tx);
-        Future future = TransactionExecutor.instance.submitTransaction(transactionTask);
+        Future<Transaction> future = TransactionExecutor.instance.submitTransaction(transactionTask);
         dialog.infoStatusMsg("Transaction sent to the network, waiting for approve");
 
         try {
             future.get(CONFIG.transactionApproveTimeout(), TimeUnit.SECONDS);
-        } catch (TimeoutException e1) {
-            e1.printStackTrace();
+        } catch (TimeoutException toe) {
+            logger.error(toe.getMessage(), toe);
             dialog.alertStatusMsg("Transaction wasn't approved, network timeout");
             return null;
-        } catch (InterruptedException e1) {
-            e1.printStackTrace();
+        } catch (InterruptedException ie) {
+        	logger.error(ie.getMessage(), ie);
             dialog.alertStatusMsg("Transaction wasn't approved");
             return null;
-        } catch (ExecutionException e1) {
-            e1.printStackTrace();
+        } catch (ExecutionException ee) {
+        	logger.error(ee.getMessage(), ee);
             dialog.alertStatusMsg("Transaction wasn't approved");
             return null;
         } finally {
diff --git a/ethereumj-core/src/main/java/org/ethereum/gui/MessageAwareDialog.java b/ethereumj-core/src/main/java/org/ethereum/gui/MessageAwareDialog.java
index 18cffe96..5343a6f9 100644
--- a/ethereumj-core/src/main/java/org/ethereum/gui/MessageAwareDialog.java
+++ b/ethereumj-core/src/main/java/org/ethereum/gui/MessageAwareDialog.java
@@ -1,16 +1,12 @@
 package org.ethereum.gui;
 
-import javax.swing.*;
-import java.awt.*;
-
 /**
- * www.ethereumJ.com
- * User: Roman Mandeleil
- * Created on: 26/05/2014 12:29
+ * This interface describes the methods required 
+ * for any dialog that displays info- and alert status messages.
  */
-
 public interface MessageAwareDialog {
-    public void infoStatusMsg(final String text);
-    public void alertStatusMsg(final String text);
 
+	public void infoStatusMsg(final String text);
+
+	public void alertStatusMsg(final String text);
 }
diff --git a/ethereumj-core/src/main/java/org/ethereum/gui/PayOutDialog.java b/ethereumj-core/src/main/java/org/ethereum/gui/PayOutDialog.java
index a922cef9..eb76932c 100644
--- a/ethereumj-core/src/main/java/org/ethereum/gui/PayOutDialog.java
+++ b/ethereumj-core/src/main/java/org/ethereum/gui/PayOutDialog.java
@@ -22,12 +22,14 @@ import javax.swing.*;
  * User: Roman Mandeleil
  * Created on: 18/05/14 22:21
  */
-class PayOutDialog extends JDialog implements MessageAwareDialog{
+class PayOutDialog extends JDialog implements MessageAwareDialog {
 
-    PayOutDialog dialog;
+	private static final long serialVersionUID = -2838121935782110981L;
 
-    AccountState addressState = null;
-    JLabel statusMsg = null;
+	private PayOutDialog dialog;
+
+    private AccountState addressState = null;
+    private JLabel statusMsg = null;
 
     final JTextField receiverInput;
     final JTextField amountInput;
@@ -124,7 +126,6 @@ class PayOutDialog extends JDialog implements MessageAwareDialog{
 				try {
 					tx.sign(senderPrivKey);
 				} catch (Exception e1) {
-
 					dialog.alertStatusMsg("Failed to sign the transaction");
 					return;
 				}
diff --git a/ethereumj-core/src/main/java/org/ethereum/gui/ProgramPlayDialog.java b/ethereumj-core/src/main/java/org/ethereum/gui/ProgramPlayDialog.java
index db905113..471984a0 100644
--- a/ethereumj-core/src/main/java/org/ethereum/gui/ProgramPlayDialog.java
+++ b/ethereumj-core/src/main/java/org/ethereum/gui/ProgramPlayDialog.java
@@ -1,8 +1,6 @@
 package org.ethereum.gui;
 
-import org.ethereum.vm.DataWord;
 import org.ethereum.vm.Program;
-import org.ethereum.vm.ProgramInvoke;
 import org.ethereum.vm.VM;
 import org.spongycastle.util.encoders.Hex;
 
@@ -12,7 +10,6 @@ import javax.swing.event.ChangeListener;
 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
-import java.awt.event.WindowListener;
 import java.util.*;
 import java.util.List;
 
@@ -22,7 +19,8 @@ import java.util.List;
  * Created on: 02/06/2014 16:58
  */
 
-public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeListener, Program.ProgramListener {
+public class ProgramPlayDialog extends JPanel implements ActionListener,
+		ChangeListener, Program.ProgramListener {
 
     public List<String> outputList;
     public JTextArea console;
@@ -95,8 +93,6 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
     @Override
     public void actionPerformed(ActionEvent e) {
 
-
-
     }
 
     @Override
@@ -111,7 +107,6 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
         console.setCaretPosition(0);
     }
 
-
     /**
      * Create the GUI and show it.  For thread safety,
      * this method should be invoked from the
@@ -119,8 +114,6 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
      */
     public static void createAndShowGUI() {
 
-
-
         ProgramPlayDialog ppd = new ProgramPlayDialog();
 
         //Create and set up the window.
@@ -130,7 +123,6 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
         frame.setPreferredSize(new Dimension(580, 500));
         frame.setLocation(400, 200);
 
-
         //Add content to the window.
         frame.add(ppd, BorderLayout.CENTER);
 
@@ -138,7 +130,6 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
         frame.pack();
         frame.setVisible(true);
         ppd.setFocus();
-
     }
 
     @Override
@@ -151,10 +142,9 @@ public class ProgramPlayDialog extends JPanel implements ActionListener, ChangeL
         /* Turn off metal's use of bold fonts */
         UIManager.put("swing.boldMetal", Boolean.FALSE);
 
-
         //Schedule a job for the event-dispatching thread:
         //creating and showing this application's GUI.
-        javax.swing.SwingUtilities.invokeLater(new Runnable() {
+        SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                 createAndShowGUI();
             }
diff --git a/ethereumj-core/src/main/java/org/ethereum/net/message/StaticMessages.java b/ethereumj-core/src/main/java/org/ethereum/net/message/StaticMessages.java
index 5027bbc7..4fa06b5b 100644
--- a/ethereumj-core/src/main/java/org/ethereum/net/message/StaticMessages.java
+++ b/ethereumj-core/src/main/java/org/ethereum/net/message/StaticMessages.java
@@ -16,7 +16,7 @@ public class StaticMessages {
     public static final byte[] GET_TRANSACTIONS = Hex.decode("2240089100000002C116");
 
     public static final byte[] DISCONNECT_08 = Hex.decode("2240089100000003C20108");
-    public static final byte[] GENESIS_HASH = Hex.decode("77ef4fdaf389dca53236bcf7f72698e154eab2828f86fbc4fc6cd9225d285c89"); // (new Genesis()).getHash();
+    public static final byte[] GENESIS_HASH = Hex.decode("77ef4fdaf389dca53236bcf7f72698e154eab2828f86fbc4fc6cd9225d285c89");
     public static final byte[] MAGIC_PACKET = Hex.decode("22400891");
 
     static {
diff --git a/ethereumj-core/src/main/java/org/ethereum/net/submit/PendingTransaction.java b/ethereumj-core/src/main/java/org/ethereum/net/submit/PendingTransaction.java
index 56f50af2..775d56c9 100644
--- a/ethereumj-core/src/main/java/org/ethereum/net/submit/PendingTransaction.java
+++ b/ethereumj-core/src/main/java/org/ethereum/net/submit/PendingTransaction.java
@@ -10,14 +10,16 @@ import org.ethereum.core.Transaction;
 
 public class PendingTransaction {
 
-    Transaction tx;
+    private Transaction tx;
     int approved = 0; // each time the tx got from the wire this value increased
 
     public PendingTransaction(Transaction tx) {
         this.tx = tx;
     }
 
-    public void incApproved(){++this.approved;}
+	public void incApproved() {
+		++this.approved;
+	}
 
     public int getApproved() {
         return approved;
diff --git a/ethereumj-core/src/main/java/org/ethereum/trie/TrieIterator.java b/ethereumj-core/src/main/java/org/ethereum/trie/TrieIterator.java
index 57c5c943..20148ebb 100644
--- a/ethereumj-core/src/main/java/org/ethereum/trie/TrieIterator.java
+++ b/ethereumj-core/src/main/java/org/ethereum/trie/TrieIterator.java
@@ -7,12 +7,12 @@ import static org.ethereum.util.CompactEncoder.unpackToNibbles;
 
 public class TrieIterator {
 	
-	Trie trie;
-	String key;
-	String value;
+	private Trie trie;
+	private String key;
+	private String value;
 
-	List<byte[]> shas;
-	List<String> values;
+	private List<byte[]> shas;
+	private List<String> values;
 
 	public TrieIterator(Trie t) {
 		this.trie = t;
diff --git a/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java b/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
index 3408a102..58e8e303 100644
--- a/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
+++ b/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
@@ -7,34 +7,31 @@ import java.math.BigInteger;
 import java.nio.ByteBuffer;
 
 /**
- * www.ethereumJ.com
- * User: Roman Mandeleil
- * Created on: 01/06/2014 19:47
+ * DataWord is the 32-byte array representation of a 256-bit number
+ * Calculations can be done on this word with other DataWords
  */
-
 public class DataWord {
 
     static DataWord ZERO = new DataWord(new byte[32]);      // don't push it in to the stack
 
     byte[] data = new byte[32];
 
-    public DataWord(){
-        data = new byte[32];
-    }
+	public DataWord() {
+		data = new byte[32];
+	}
 
-    public DataWord(int num){
-        ByteBuffer bInt   = ByteBuffer.allocate(4).putInt(num);
-        ByteBuffer data    =  ByteBuffer.allocate(32);
-        System.arraycopy(bInt.array(), 0, data.array(), 28, 4);
-        this.data = data.array();
-    }
+	public DataWord(int num) {
+		ByteBuffer bInt = ByteBuffer.allocate(4).putInt(num);
+		ByteBuffer data = ByteBuffer.allocate(32);
+		System.arraycopy(bInt.array(), 0, data.array(), 28, 4);
+		this.data = data.array();
+	}
 
-    public DataWord(byte[] data){
-        if (data == null || data.length > 32)
-            throw new RuntimeException("bad push data: " +  data);
-
-        System.arraycopy(data, 0, this.data, 32 - data.length,  data.length);
-    }
+	public DataWord(byte[] data) {
+		if (data == null || data.length > 32)
+			throw new RuntimeException("bad push data: " + data);
+		System.arraycopy(data, 0, this.data, 32 - data.length, data.length);
+	}
 
     public byte[] getData() {
         return data;
@@ -95,9 +92,20 @@ public class DataWord {
         }
     }
 
-    // todo: add can be done in more efficient way
-    // todo      without BigInteger quick hack
-    public void add(DataWord word){
+    // By	: Holger
+    // From	: http://stackoverflow.com/a/24023466/459349
+    public void add(DataWord word) {
+		byte[] result = new byte[32];
+		for (int i = 31, overflow = 0; i >= 0; i--) {
+			int v = (this.data[i] & 0xff) + (word.data[i] & 0xff) + overflow;
+			result[i] = (byte) v;
+			overflow = v >>> 8;
+		}
+		this.data = result;
+    }
+    
+    // old add-method with BigInteger quick hack
+    public void add2(DataWord word){
 
         BigInteger result = value().add( word.value() );
         byte[] bytes = result.toByteArray();
@@ -106,11 +114,11 @@ public class DataWord {
         System.arraycopy(bytes, 0, data.array(), 32 - bytes.length, bytes.length);
         this.data = data.array();
     }
-
-    // todo: mull can be done in more efficient way
+    
+    // todo: mul can be done in more efficient way
     // todo:     with shift left shift right trick
     // todo      without BigInteger quick hack
-    public void mull(DataWord word){
+    public void mul(DataWord word){
 
         BigInteger result = value().multiply( word.value() );
         byte[] bytes = result.toByteArray();
diff --git a/ethereumj-core/src/main/java/org/ethereum/vm/VM.java b/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
index 52e51166..e0726e1b 100644
--- a/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
+++ b/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
@@ -55,7 +55,7 @@ public class VM {
 
                     DataWord word1 = program.stackPop();
                     DataWord word2 = program.stackPop();
-                    word1.mull(word2);
+                    word1.mul(word2);
                     program.stackPush(word1);
                     program.step();
                 }
diff --git a/ethereumj-core/src/main/resources/system.properties b/ethereumj-core/src/main/resources/system.properties
index aaa27411..8925ac14 100644
--- a/ethereumj-core/src/main/resources/system.properties
+++ b/ethereumj-core/src/main/resources/system.properties
@@ -69,4 +69,4 @@ samples.dir = samples
 # the existing database will be 
 # destroyed and all the data will be 
 # downloaded from peers again
-database.reset = true
+database.reset = false
diff --git a/ethereumj-core/src/test/java/org/ethereum/core/BlockTest.java b/ethereumj-core/src/test/java/org/ethereum/core/BlockTest.java
index 12f09aa9..2210d050 100644
--- a/ethereumj-core/src/test/java/org/ethereum/core/BlockTest.java
+++ b/ethereumj-core/src/test/java/org/ethereum/core/BlockTest.java
@@ -22,7 +22,7 @@ public class BlockTest {
     	// from RLP encoding
     	byte[] genesisBytes = Hex.decode(CPP_PoC5_GENESIS_HEX_RLP_ENCODED);
     	Block genesisFromRLP = new Block(genesisBytes);
-    	Genesis genesis = new Genesis();
+    	Block genesis = Genesis.getInstance();
     	assertEquals(Hex.toHexString(genesis.getHash()), Hex.toHexString(genesisFromRLP.getHash()));
     	assertEquals(Hex.toHexString(genesis.getParentHash()), Hex.toHexString(genesisFromRLP.getParentHash()));
     	assertEquals(Hex.toHexString(genesis.getStateRoot()), Hex.toHexString(genesisFromRLP.getStateRoot()));
@@ -48,7 +48,7 @@ public class BlockTest {
         				B32(sha3(B(42)))
         			)
          */
-    	Block genesis = new Genesis();
+    	Block genesis = Genesis.getInstance();
         assertEquals(CPP_PoC5_GENESIS_HEX_RLP_ENCODED, Hex.toHexString(genesis.getEncoded()));
         
         // Not really a good test because this compares Genesis.getHash() to itself
diff --git a/ethereumj-core/src/test/java/org/ethereum/vm/DataWordTest.java b/ethereumj-core/src/test/java/org/ethereum/vm/DataWordTest.java
new file mode 100644
index 00000000..229c0860
--- /dev/null
+++ b/ethereumj-core/src/test/java/org/ethereum/vm/DataWordTest.java
@@ -0,0 +1,71 @@
+package org.ethereum.vm;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+import org.spongycastle.util.encoders.Hex;
+
+public class DataWordTest {
+
+	@Test
+	public void testAddPerformance() {
+		boolean enabled = true;
+		
+		if(enabled) {
+			byte[] one = new byte[] { 0x01, 0x31, 0x54, 0x41, 0x01, 0x31, 0x54,
+					0x41, 0x01, 0x31, 0x54, 0x41, 0x01, 0x31, 0x54, 0x41, 0x01,
+					0x31, 0x54, 0x41, 0x01, 0x31, 0x54, 0x41, 0x01, 0x31, 0x54,
+					0x41, 0x01, 0x31, 0x54, 0x41 }; // Random value
+			
+			int ITERATIONS = 10000000;
+			
+			long now1 = System.currentTimeMillis();
+			for (int i = 0; i < ITERATIONS; i++) {
+				DataWord x = new DataWord(one);
+				x.add(x);
+			}
+			System.out.println("Add1: " + (System.currentTimeMillis() - now1) + "ms");
+				
+			long now2 = System.currentTimeMillis();
+			for (int i = 0; i < ITERATIONS; i++) {
+				DataWord x = new DataWord(one);
+				x.add2(x);
+			}
+			System.out.println("Add2: " + (System.currentTimeMillis() - now2) + "ms");
+		} else {
+			System.out.println("ADD performance test is disabled.");
+		}
+	}
+
+	@Test
+	public void testAdd2() {
+		byte[] two = new byte[32];
+		two[31] = (byte) 0xff; // 0x000000000000000000000000000000000000000000000000000000000000ff
+		
+		DataWord x = new DataWord(two);
+		x.add(new DataWord(two));
+		System.out.println(Hex.toHexString(x.data));
+		
+		DataWord y = new DataWord(two);
+		y.add2(new DataWord(two));
+		System.out.println(Hex.toHexString(y.data));
+	}
+	
+	@Test
+	public void testAdd3() {
+		byte[] three = new byte[32];
+		for (int i = 0; i < three.length; i++) {
+			three[i] = (byte) 0xff;
+		}
+		
+		DataWord x = new DataWord(three);
+		x.add(new DataWord(three));
+		assertEquals(32, x.data.length);
+		System.out.println(Hex.toHexString(x.data));
+
+		// FAIL
+//		DataWord y = new DataWord(three);
+//		y.add2(new DataWord(three));
+//		System.out.println(Hex.toHexString(y.data));
+	}
+}
diff --git a/ethereumj-core/src/test/java/org/ethereum/vm/ProgramInvokeMockImpl.java b/ethereumj-core/src/test/java/org/ethereum/vm/ProgramInvokeMockImpl.java
index a23b983b..f7257730 100644
--- a/ethereumj-core/src/test/java/org/ethereum/vm/ProgramInvokeMockImpl.java
+++ b/ethereumj-core/src/test/java/org/ethereum/vm/ProgramInvokeMockImpl.java
@@ -4,8 +4,6 @@ import org.ethereum.crypto.ECKey;
 import org.ethereum.crypto.HashUtil;
 import org.spongycastle.util.encoders.Hex;
 
-import java.util.List;
-
 /**
  * www.ethereumJ.com
  * User: Roman Mandeleil
diff --git a/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java b/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
index 40f03122..1d038f3a 100644
--- a/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
+++ b/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
@@ -1,6 +1,5 @@
 package org.ethereum.vm;
 
-import org.ethereum.crypto.HashUtil;
 import org.junit.Test;
 import org.spongycastle.util.encoders.Hex;