Race condition solved:

+  new SHA3Digest(256) - can't be shared, it's not a thread safe class

ethereumj-core/src/main/java/org/ethereum/core/Blockchain.java

@@ -56,6 +56,10 @@ public class Blockchain {
             return lastBlock;
 	}
 
+    public void setLastBlock(Block block){
+            lastBlock = block;
+    }
+
     public int getSize(){
         return index.size();
     }
@@ -111,8 +115,8 @@ public class Blockchain {
 	        // on this price will use default 10000000000000
 	        // todo: refactor this longValue some constant defaults class 10000000000000L
 			this.gasPrice = block.isGenesis() ? INITIAL_MIN_GAS_PRICE : block.getMinGasPrice();
-			if(lastBlock == null || block.getNumber() > lastBlock.getNumber()){
-				this.lastBlock = block;
+			if(getLastBlock() == null || block.getNumber() > getLastBlock().getNumber()){
+				setLastBlock( block );
                 index.put(block.getNumber(), block.getParentHash());
             }
     	}
@@ -153,7 +157,7 @@ public class Blockchain {
             if (index.isEmpty())
                 return StaticMessages.GENESIS_HASH;
             else
-			return lastBlock.getHash();
+                return getLastBlock().getHash();
     }
     
 	public void loadChain() {
@@ -171,8 +175,8 @@ public class Blockchain {
 				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();					
+						logger.debug("Block: " + getLastBlock().getNumber() + " ---> " + getLastBlock().toFlatString());
+					parentHash = getLastBlock().getHash();
 				}
 			}
 		} finally {

ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java

@@ -7,22 +7,20 @@ import org.spongycastle.util.encoders.Hex;
 
 public class SHA3Helper {
 	
-	private static SHA3Digest DEFAULT_DIGEST_256 = new SHA3Digest(256);
-
 	public static String sha3String(String message) {
-		return sha3String(message, DEFAULT_DIGEST_256, true);
+		return sha3String(message, new SHA3Digest(256), true);
 	}
 	
 	public static String sha3String(byte[] message) {
-		return sha3String(message, DEFAULT_DIGEST_256, true);
+		return sha3String(message, new SHA3Digest(256), true);
 	}
 
 	public static byte[] sha3(String message) {
-		return sha3(Hex.decode(message), DEFAULT_DIGEST_256, true);
+		return sha3(Hex.decode(message), new SHA3Digest(256), true);
 	}
 	
 	public static byte[] sha3(byte[] message) {
-		return sha3(message, DEFAULT_DIGEST_256, true);
+		return sha3(message, new SHA3Digest(256), true);
 	}
 	
 	protected static String sha3String(String message, Size bitSize) {

ethereumj-core/src/main/java/org/ethereum/net/client/EthereumProtocolHandler.java

@@ -256,8 +256,6 @@ public class EthereumProtocolHandler extends ChannelInboundHandlerAdapter {
 
             MainData.instance.getBlockchain().addBlocks(blockList);
             WorldManager.instance.applyBlockList(blockList);
-
-            logger.info(blocksMessage.toString());
             if (peerListener != null) peerListener.console(blocksMessage.toString());
         }
 

ethereumj-core/src/main/resources/system.properties

@@ -16,8 +16,8 @@ peer.discovery.port = 30303
 # that is the peer through
 # we get the chain: [54.201.28.117] port: [30303]
 # ZeroGox
-#peer.active.ip = 54.204.10.41
-#peer.active.port = 30303
+peer.active.ip = 54.204.10.41
+peer.active.port = 30303
 
 # Some dude in Canada
 #peer.active.ip = 131.104.247.135
@@ -29,8 +29,8 @@ peer.discovery.port = 30303
 
 
 # RomanJ general
-peer.active.ip = 54.211.14.10
-peer.active.port = 50505
+#peer.active.ip = 54.211.14.10
+#peer.active.port = 50505
 
 #peer.active.ip = 151.64.223.120
 #peer.active.port = 30304