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Indeed. But still realized that even if you insert a long wait, there is still no guarantee your consumer will execute. If the system is under load from another process (LabVIEW or otherwise), a few seconds still might not be enough. The behavior is by it's very nature undefinable. As LogMAN said, you can also consider adding other synchronization functionality. Passing an occurrence or rendezvous as part of the stop event works, and then the code that trips the stop event can wait for the sync object to be properly signalled before destroying the event registration. But I still believe letting the consumer handle the unregistration is the best way to do it. For the very reason your code is giving you problems, I try to always tie event unregistration with the same event structure that owns/uses the registration.