For our Chat tool, we use the Wildfire Jabber Server. See the Installing Wildfire page.
D:\ (Windows) | /usr/local/jboss-4.0.2 (Unix)
4.0.3SP1 and 4.0.4 have problems running LAMS, so 4.0.2 is your best bet until we fix the problem.
Check that you have the latest LAMS 2 Unix installer