Here are the usual suspects: 1) Try using JDK 1.5 instead of 1.6. 1.6 is not officially supported on AS 4.0.5. 2) Double-check your /etc/hosts files that the entries are correct. If you are not sure, post yours. 3) Check your firewall. My understanding is that Ubuntu is desktop-oriented, not server-oriented, and thus you need to do more configuration work to use it as a server. 4) How did you install? Unzipping the binary zip download, or running the installer JAR? If the latter, try reinstalling but not selecting clustering (use a 'default' configuration rather than an 'all' configuration). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4082365#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...