Hi, I have the same problem with JBoss 4.0.5 (ClassCastException when trying to narrow an EJB interface retrieved via a JNDI lookup). As with you, my WAR and EJB are colocated in a single Jboss instance. I figured setting "Call by Value" semantics everywhere would fix this (assuming the usual JBoss flat-classloader issues) - however that did not resolve the problem in 4.0.5 !?!? Have you made any further progress ?? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3984416#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...