Blinking & blanking screen

I've read posts in this topic but I don't think my issue is overheating hardware. Under Win 7 Ultimate, my monitor will go black, blink between black and a display, etc. when I sometimes have dialog boxes open. Never does it with just the desktop showing. It seems inconsistent re which program it is in at the time; I've not found a pattern and I can't do a certain set of steps to induce the consdition. Sometimes moving the mouse will get the display back for a moment then it blanks again. Making another window the active one will sometimes clear it up, but again, no pattern of behaviour I can spot. Ctrl-Alt-Del will open the task manager screeen and pull me out of the condition but if I click to go back to Windows the condition resumes. When I kill one or a few windows the condition clears; sometimes I can do this between the blinking screen other times I've had to go in to the computer remotely because I'm stuck with a blank screen. I have an EVGA GeForce 6800 video card and have loaded the latest driver. Indicator on monitor shows there is a signal (as compared to no video coming to the monitor) but what I see is black.

Try a different input to the card too. I'd replace the card. A 5570 would butcher it in terms of performance, assuming your PCI-E slot is v2.

I've found out more about the blinking screens. I HAVE updated my driver. It depends on the screen. If I have multiple windows open, one or more may cause the blanking, with mouse movement getting it back for a moment. If I alt-tab to another window (even if the current display is blank) that display can be fine. Alt-tab back to the first and display will blank. I've had several times where I thought I had a pattern of behaviour but that've not stood the test of time. Sometimes reducing screen resolution will make it better but not always. Ctrl-Alt-Del always takes me out to a visible screen, but if I choose to go back to the "regular" display and that was a blanked screen, display will blank again. This same computer, PS and display adapter woirked fine with XP. It is a GeForce 6800 series and has its own PS connection.

What are your power supply specs?