Solved it myself... After googling quite a while, I learned many things about configuration and library versions. One of it is that I needed ehcache-1.2 instead of 1.1. But that didn't help at first, until I found out that Netbeans doesn't copy anymore the *.ear file to the deploy directory before starting the server (probably some permission problem, will figure that out later). However, it seems to work now. Many thanks to anyone who tryed to reproduce it. /R View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3962472#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...