I have fixed the problem. It is hibernate updating the database on startup that is the problem. By changing | <property name="hibernate.hbm2ddl.auto" value="update"/> | to | <property name="hibernate.hbm2ddl.auto" value="none"/> | in persistence.xml fixed the issue. <no-tx-seperate-pools/> should also fix this but it doesn't. Perhaps the version of JBoss I am using doesn't support this?! Thank you Adrian and Weston for all your help. I am very grateful for all the time you put into this. Cheers. Adrian View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4009567#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...