tsar is correct. I have no problem running JDK 6 update 1 with JBoss 4.2.0.GA on win XP PRO sp2 fully patched. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4047020#4047020 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4047020