For what it's worth I would say that Application.ProcessMessages is asking for trouble. It sets up your code for a re-entrancy problem that it is highly unlikely to cater for adequately (as you already found once, but user input isn't the only potential source of messages that could cause re-entrancy issues for your busy-wait loop).<br>
<br>If anything, I think the fact that this loop is (presumably) running on the main thread in your app could be the source of your lock up issues, precisely because of the need to keep that thread happily pumping your applications message queue.<br>
<br>What is this busy-loop used for ? Can you not devise some other mechanism to achieve the same result without having to go into a busy-wait loop and putting the message loop on heart-bypass while you do so ?<br><br>Maybe a waitable timer ?<div>
Or an event ?</div><div><br></div><div>(i.e. a "proper" thread synchronization technique, which is what this appears to be trying to achieve)<br><br><br>Just a suggestion,</div><div><br></div><div>Jolyon</div>