"Unfortunately", the problem cannot be related to multiple durable subscribers: we tried it with only one durable subscriber, and it still happened. Now I'm really clueless. We're going to try to move some memory-intensive processing to a different node so the MessageCache has more memory and is less likely to swap out and, in consequence, load messages from DB. Anyway, and just to stir some more reaction, doesn't JBOSS care about NPEs happening in their code? I'd think this one really shouldn't happen, as the user cannot do anything about it. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3981070#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...