There is a session leak in the tomcat version currently in jboss.
We seem to be running into this quite frequently. As a result of which we have to restart the server.
We found a bug report on apache
http://issues.apache.org/bugzilla/show_bug.cgi?id=37356


Seems as though it is fixed in 5.5.21. Any chance of upgrading jboss 4.0.5 to use tomcat 5.5.21