Nope.

It sort of sounds like your form got closed somehow, but you have other  
thread that are not background threads (that is, specifically marked as  
background with the IsBackground property).  It could be as simple as an  
application that doesn't shut things down when the main form gets closed,  
and then some user accidently closing the form, or some sort of bug that  
causes the form to sponaneously close or be hidden.

I would say the first thing to do is override the OnFormClosed method, and  
maybe also the OnVisibleChanged method, and include some sort of logging  
or user alert to help you know if and when the form is closed or hidden.  
If you can reproduce the issue in a debugger-friendly setting, go so far  
as to include a call to Debugger.Break() in those methods, so that the  
application just stops and you can take a look at what's closing the form.

If you want to get really fancy, I suppose you could do some tricks with  
suspending the thread from a different thread, getting a stack trace, and  
then allowing the main thread to continue.  That may be overkill though,  
depending on what else you can do.

Pete