Originally Posted by
aurik
I think it's your eyes man. Go see a doctor.
When it goes black, is it like a flicker, does it come back? Or is the picture gone for a long time? Are you on a flat panel monitor? That sort of thing happens when it gets confused and resynchs. If you haven't installed anything different since it started happening, check the monitor cables.
If you have another monitor in the house, try plugging that in. It could be the card or the monitor that is on the fritz (I had a monitor cable port die on me once; card was fine, monitor was fine, but I could only use the analog output from the card for some reason).
You should try to isolate exactly which part is malfunctioning.