Failed to load Ljava.util.concurrent.ConcurrentHashMap$Segment;

2009-01-06 18:11:26,923 FATAL [BAM::ip-10-250-150-114.ec2.internal::Agent] [AgentContext] Agent encountered fatal error.  Exiting.
java.io.IOException: HTTP status code 500 received in response to GET request for Ljava.util.concurrent.ConcurrentHashMap$Segment;.
	at com.atlassian.bamboo.agent.bootstrap.AgentContext.httpException(AgentContext.java:24)
	at com.atlassian.bamboo.agent.bootstrap.AgentClassLoader.findClass(AgentClassLoader.java:139)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
	at com.atlassian.bamboo.agent.bootstrap.AgentClassLoader.loadClass(AgentClassLoader.java:295)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
	at org.apache.activemq.util.ClassLoading.load(ClassLoading.java:112)
	at org.apache.activemq.util.ClassLoading.loadClass(ClassLoading.java:51)
	at org.apache.activemq.util.ClassLoading.loadClass(ClassLoading.java:78)
	at org.apache.activemq.util.ClassLoadingAwareObjectInputStream.load(ClassLoadingAwareObjectInputStream.java:55)
	at org.apache.activemq.util.ClassLoadingAwareObjectInputStream.resolveClass(ClassLoadingAwareObjectInputStream.java:37)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496)
	at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1624)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1323)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
	at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:480)
	at java.util.concurrent.ConcurrentHashMap.readObject(ConcurrentHashMap.java:1265)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
	at org.apache.activemq.command.ActiveMQObjectMessage.getObject(ActiveMQObjectMessage.java:166)
	at org.springframework.jms.support.converter.SimpleMessageConverter.extractSerializableFromMessage(SimpleMessageConverter.java:222)
	at org.springframework.jms.support.converter.SimpleMessageConverter.fromMessage(SimpleMessageConverter.java:109)
	at org.springframework.jms.core.JmsTemplate.doConvertFromMessage(JmsTemplate.java:763)
	at org.springframework.jms.core.JmsTemplate.receiveSelectedAndConvert(JmsTemplate.java:742)
	at com.atlassian.bamboo.v2.build.queue.AgentQueueAccessorImpl.takeBuildContext(AgentQueueAccessorImpl.java:29)
	at com.atlassian.bamboo.v2.build.agent.BuildAgentControllerImpl.waitAndPerformBuild(BuildAgentControllerImpl.java:65)
	at com.atlassian.bamboo.v2.build.agent.DefaultBuildAgent$1.run(DefaultBuildAgent.java:101)
	at com.atlassian.bamboo.build.pipeline.concurrent.NamedThreadFactory$1.run(NamedThreadFactory.java:32)
	at edu.emory.mathcs.backport.java.util.concurrent.helpers.ThreadHelpers$1.run(ThreadHelpers.java:34)
	at java.lang.Thread.run(Thread.java:619)