How are you packaging your app? might be a classloader visibility problem, there's been a fix to that rather recently, is it possible for you to try with the latest 3.2.2RC4 and see if it has the same problem?
I solved the problem! It was not jboss-problem but my mistake! I didn't pack everything correctly and jboss didn't found the classes!
So now I have another question,
When I start JBoss, it takes very long until it creates a PersistenceManager (PM)! The default PM by JBoss 3.2.1 is jdbc2 "org.jboss.mq.pm.jdbc2.PersistenceManager" (by JBoss 3.0 it was the file PersistentManager "org.jboss.mq.pm.file.PersistenceManager") and it was not that slow.
My problem is now, that when I use another PM (file-PM or rolling-PM) then JBoss fails to start MessageCashe!
I also uncommented the optional atribute "CasheStore" but vainly!