We are struggling with the same kind of problems. Tomcat gets unresponsive after a while and sometimes we can see an OutOfMemoryError but not always. We are running jboss 4.0.3_SP1 in a cluster with apache in front, java version is 1.5.0_11 and os is RedaHat EL. The problem seams only to affect tomcat and the rest of jboss e.g. seams to run ok. From jstats we see that most threads are "BLOCKED" and the ones that are not are in "IN_NATIVE" state doing either socketAccespt, socketRead or receive. We cannot see any correlation to the load on the server, we can provoke this with only one user. However, it occurs most irregular, sometimes several times pers day sometimes a week can go by. Would appreciate all hints that could help us solve this problem Cheers! /Andras View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4040482#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...