ConcurrentModificationException

Caused by: javax.ejb.EJBException: JBAS018688: Exception in store of entity: 710304
at org.jboss.as.cmp.TransactionEntityMap$GlobalTxSynchronization.synchronize(TransactionEntityMap.java:317) [jboss-as-cmp-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
at org.jboss.as.cmp.TransactionEntityMap.synchronizeEntities(TransactionEntityMap.java:214) [jboss-as-cmp-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
at org.jboss.as.cmp.component.CmpEntityBeanComponent.synchronizeEntitiesWithinTransaction(CmpEntityBeanComponent.java:104) [jboss-as-cmp-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
at org.jboss.as.cmp.component.interceptors.CmpEntityBeanHomeFinderInterceptorFactory.invokeFind(CmpEntityBeanHomeFinderInterceptorFactory.java:69) [jboss-as-cmp-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
at org.jboss.as.ejb3.component.entity.interceptors.EntityBeanHomeFinderInterceptorFactory$1.processInvocation(EntityBeanHomeFinderInterceptorFactory.java:92) [jboss-as-ejb3-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.1.Final-redhat-1.jar:1.1.1.Final-redhat-1]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInCallerTx(CMTTxInterceptor.java:201) [jboss-as-ejb3-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
... 90 more
Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819) [rt.jar:1.7.0_09]
at java.util.ArrayList$Itr.next(ArrayList.java:791) [rt.jar:1.7.0_09]
at org.jboss.as.cmp.TransactionEntityMap$GlobalTxSynchronization.synchronize(TransactionEntityMap.java:278) [jboss-as-cmp-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
... 96 more