It's probably JBossMQ. You may want to keep an eye on this issue. The necessary recovery work was done over a year ago, but it hasn't been pulled into the latest releases. Hopefully the team will get to this soon.
Thanks for the reply.
If JBossMQ is the problem, would it then be solved by replacing it with JBoss Messaging? In other words: Is the necessary work done in JBoss Messaging?
Yes, JBoss Messaging has had recovery integration with JBossTS for a while.