I've just had the same exception using JBOSS 6.0.0.Final and a JDK 6.
The issue was the version of the JDK.
I first used OpenJDK 1.6.0_34. I had this exception when starting the application server.
I installed the Oracle JDK 6 (1.6.0_45) and the problem disappeared.
I assume it is worth trying something like this also in your case (check your JDK version as well as your JDK vendor).