Hello, We have an application in production that uses a singletion mdb that reads in a queue. It worked perfectly for months but today we suddenly noticed that the mdb wasn't reading the queue anymore. We restarted our jboss 4.2.0 server but it solved nothing. Finally we had to delete the data/tx-object-store and data/xmbean-attrs to make it finally work. We had no time to check for logs since we are already in production. What can be the causes ?