Is it a dodgy cable? Or is it a dodgy graphics card?
This could blank the picture for a while. Whether there is a way that can be fed back to the pc to say that there is a display fault, I'm not 100% sure. But the pc can detect what sort of monitor/graphics you're using. This feedback might give a funny signal that makes the thing hang and need to restart explorer.
A good, but gentle, wiggle of the monitor cable plug on the bag of the pc might help show the fault up.