5.0 introduces a new classloader mechanism based on the virtual file system (VFS). Prior to 5.0 there was the unified classloader scheme. And yes, the VFS classloader is having its fair share of classloading issues, among them in beta4 it broke the isolation requirement for war files that you mentioned. Looks like it is still broke in trunk. Sigh. (It also broke classloader repository class scoping in beta3, which was still broke in beta4. If you dig through the forums, there were discussions about all of this earlier.) View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4155720#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...