When we see the clients hanging there are no threads running in any of our code (as viewe by jstack and by the thread dump in the jmx-console).
We don't see anything useful in the jboss nor server logs on the client nor server side (i.e errors, network interface messages, etc.)
What we've done is updated jboss-remoting.jar to version 2.5.2.SP3 on all of the clients and on the jboss servers.
We have not seen any issues since then.
I will update this if we start seeing them again.
Thanks for the info about setting the timeouts.
That will be useful if we do start seeing this again.
(btw, is that documented somewhere?)