Thanks for the quick answer. The server is not under heavy load, we have seen this problem just after startup when no more than 2 or 3 users are active. Admittedly 2 users are using a EJB3-heavy (i.e. lots of bean cross references, fetch joins etc) page simultaenously. We have had problems with JVM options before, mainly because we use JasperReports which eats alot of PERM space. But in this particular case JasperReports has not been active. My current thinking is to disable the connection checker and use connection-sql strings instead and see what happens. Dave View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3989316#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...