from what I can see JBoss support group is completely incapable of responding to such repeatable error. Good luck. I have posted large number of questions here and I have never received any answer from anyone.
Do you happen to have a log4j.jar file in your application (EAR, WAR, SAR, etc)? JBoss has it's own log4j and b/c of some classloading issues, you have to use their version. If you want to upgrade, you gotta upgrade the log4j.jar in server/(default|all|minimal)/lib.