Hi Tim, thanks for your quick response! The clients that put messages on the queue are Web Services that exist on two nodes in our messaging cluster. Their responsibility is to send the SOAP message to a queue that our ESB servers listen to. The ESB service performs it's actions, and one of these is to send a response message to a response queue. It's a little difficult for me to post the actual code. But the "test" class in my previous post can simulate the behaviour. This can be done with at two node messaging cluster. Are there any test in the messaging project that I could run against our configuration to verify that we have not incorrectly configured something. The system has been running in production for several month without any warnings or errors. We upgraded to 1.4.0.SP3 right before Christmas. Thanks, Daniel View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4126490#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...