Seemingly when I pass a Vector, ArrayList or some other concrete collection from a stateless session bean, when I come to do the iteration and thereby casting of the objects, it throws a ClassCastException in the iter.next() statement. Is there something I am doing wrong.

I am running JBoss 4.0.3SP1 on Win 2k (SP4) with Java SDK 1.4.2_10 and Hibernate 3.1RC2 (same as that which comes with JBoss).

Note that the collection iterates fine at the Session Bean end, so its not Hibernate related.