Peper sent me his code, and the fix was related to Classloading in JBoss. Reference: http://wiki.jboss.org/wiki/Wiki.jsp?page=ClassLoading Peper had an EAR, and in it, a WAR and EJB3 JAR. Within the WAR WEB-INF/classes were class files also defined in the EJB3 JAR. Because more than one classloader was picking up duplicates of the class definitions, the WAR-scoped classloader was attempting to cast the object retrieved from JNDI (of type recognized by the EJB3 JAR Classloader) and cast it (incorrectly) into its own version. I'm not the most succinct at explaining this, I'm sure, so check the references above for a much more detailed and correct description. Steps I took to get this to work: * Download and unzip/untar JBoss 4.2.0GA * Delete the WEB-INF/classes directory from the WAR in the EAR * Deploy the EAR S, ALR View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4046242#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...