Crashes on Exit

[Werdna LB]

I have a Duel Core AMD 4200+ and a Geforce 7600 GT. I've done all the messing around to get the game working and for the most part it works 99% of the time (still crashes out occassionally if I've been playing too long).

 

The only problem I have left is whenever I exit from the game (the whole game...with the X in the corner) my screen goes black and I have to reboot the PC.

 

Does anyone know how I can fix this???

 

It doesn't happen everytime (4/5 times) and I'm sick of just keeping it running in the background as I do other things because I can't quit.

 

Thanks,