2007-09-03 14:58:50,737 WARN [org.jboss.system.ServiceController] Problem starting service jboss.j2
ee:ear=jbilling.ear,jar=jbilling.jar,name=com/xxx/yyy/server/item/ItemSession,service=EJB3
java.lang.ClassCastException: $Proxy76 cannot be cast to javax.naming.Context
at org.jboss.util.naming.Util.createSubcontext(Util.java:69)
at org.jboss.util.naming.Util.rebind(Util.java:125)
at org.jboss.util.naming.Util.rebind(Util.java:113)
at org.jboss.ejb3.stateless.StatelessRemoteProxyFactory.start(StatelessRemoteProxyFactory.java:115)

In EJB 3 a stateful session bean can be created directly via a loopup on it's business interface. By default this one is bound to <ejb-name>/remote (or /local). The home interface is bound to <ejb-name>/home (or /localHome). If you override the JNDI name for the bean by <ejb-name> then this exception occurs. The log file should show "Binding proxy for <ejb-name> in JNDI at <jndi-name>" just before this happens.

It should say an error message in the likes of:
"Can't bind ItemSession/remoteHome, because ItemSession is already bound"