If you want to get rid of the bug in concurrent.jar, just copy the concurrent.jar of the JBoss 3.2.4 distribution in your 3.2.3 local copy.
I already tried it and it did not work.
The workaround in 3.2.4 avoids a so called race condition in concurrent.jar by introducing a MinPoolSize for the message driven container.
By the way, I don't think the singelton solution scales very well with one node handling all jms connections. I would rather have a 3.2.2 JMS framework with the fix for the message driven container problem.
If you're using java:/JmsXA there is also another difference in 3.2.4: you have to start the connection if you want to receive messages ...
Don't ask me ...