If there any way to show us what you mean.by black screen flash.
What happens when you see the flash.
could be a graphics-card related process. Regardless of cause, you might be able to trap it by:
1) open task-manager,
2) display processes and sort by %CPU
3) position mouse over the second process*
4) When screen goes black, click mouse (once).
5) When screen returns, look for blue-highlighted process
- there's a reasonable chance that screen black-out is related to that process.
All so try looking in your event viewer if you don't have it disabled.
Hope it helps!
Is this what you are talking about