Is the problem intermittent?

An intermittent problem could be caused by failing to take into account the fact that processes can run independently of each other. For example, a program might issue an MQGET call, without specifying a wait option, before an earlier process has completed. You might also encounter this if your application tries to get a message from a queue while the call that put the message is in-doubt (that is, before it has been committed or backed out).