[mythtv] MediaMonitor and system lockups

[J. Donavan Stanley]

I've seen reports of the media monitoring code causing system lock ups 
but I'd never been able to repro it.  My most recent machine I built, 
however, locked up every time I used it.  The difference between it and 
the others is the QT version.  Sure enough, upgrading it to QT 3.2 from  
QT 3.1 stopped the lockup.

For some reason the system hangs right after the media hander posts an 
event to the main thread to deal with the new disk.  The event handler 
for the ExitToMainMenu event never seems to get called.