We are running into this issue when we restart HQ.

2011-05-25 13:33:28,077 ERROR [org.hornetq.core.postoffice.impl.PostOfficeImpl] (hornetq-expiry-reaper-thread) failed to expire messages for queue MessageBridge\.ListenHQ.MessageBridge\.Sub\.TRADING\.CASHEQT\.UPDATE\.BRIDGE
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:848)
at java.util.HashMap$KeyIterator.next(HashMap.java:883)
at org.hornetq.core.postoffice.impl.PostOfficeImpl.cleanupInternalPropertiesBeforeRouting(PostOfficeImpl.java:815)
at org.hornetq.core.postoffice.impl.PostOfficeImpl.route(PostOfficeImpl.java:591)
at org.hornetq.core.postoffice.impl.PostOfficeImpl.route(PostOfficeImpl.java:556)
at org.hornetq.core.server.impl.QueueImpl.move(QueueImpl.java:1839)
at org.hornetq.core.server.impl.QueueImpl.expire(QueueImpl.java:846)
at org.hornetq.core.server.impl.QueueImpl.expireReferences(QueueImpl.java:1064)
at org.hornetq.core.postoffice.impl.PostOfficeImpl$Reaper.run(PostOfficeImpl.java:1240)
at java.lang.Thread.run(Thread.java:662)