I suggest you should use Jboss 3.0.1 rather than Jboss 3.0.0 for CMR, because I also had a lot of problems using Jboss 3.0.0 with CMR. Jboss 3.0.1 seems to be very stable for this purpose, and I do not have any problems any more.
Hope it helps.
Thanks for the tip! I downloaded the 3.0.1 and the problem goes away!