Yep. There's the issue. We discourage putting the driver in the EAR/WAR/lib directory for this very reason. Unfortunately, the JDBC DriverManager, as well as most XADataSource implementations have significant classloader caching/loading issues that make inclusion of the drivers in the deployment modules difficult. Similarly, because WAR files have their own classloading architecture, independent of the JBoss ClassLoader, you are seeing a ClassClassException. Easiest thing to do is put the JDBC jar file in your server/lib directory. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4009025#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...