As noted in the question, the JBoss 4.2.1 server has been upgraded to 7.1.1 Final. Upgrading has resolved the issue and the client now works as expected, but unfortunately this solution does not explain the problem.
As noted in the question, the JBoss 4.2.1 server has been upgraded to 7.1.1 Final. Upgrading has resolved the issue and the client now works as expected, but unfortunately this solution does not explain the problem.