Okay I resolved this issue. Using the log4j appender for UCL I was able to track down that the utility jar I was deploying in my EAR was using a facet for Java set to version 6.0 and the container is running in a 5.0 JVM. Because of this the UnifiedClassLoader was not willing to load unmatched version of any classes into the JVM. Updating the facet to java 5.0 fixed this. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3986849#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...