The issue I see is that Hibernate can't load classes when it does a transaction commit, after a JMS message is processed in an MDB. See this thread: http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4068315 When does Thread.setCurrentClassLoader() get called for messages being processed in an MDB? It seems this is somehow reset, perhaps post processing. JBoss AS /connector does not set the classloader. Looking at the Hibernate sources, Hibernate does not make this call. So I assume it's part of JBoss Messaging (the JmsSession), and it must get reset before transaction commit. Anyway, it's a definite bug, I just need to know where the bug is. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4068318#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...