Windows fails to detect my video card

After playing for like 2-5 hours Windows fails to detect my video card and if I exit the current game I am in then I am unable to enter any other game. (including the one I was in before)
I believe the problem stands with windows failing to detect the driver or something of the sort. Note that if this bug/error occurs I am not receiving a crash if I play a game. I can play that game as much as I want without any visual artifacts until I exit.
I can't make a screenshot of any sort. (can't copy from clipboard data)
It's like I don't got a video card anymore after some time. Once I restart PC I can use it again for 2-5 hours.
Any suggestions what it may actually be? My fan temperature is fine it still shows green.
Sorry if this isn't in the right section.. just this is my best guess as to what could be wrong (windows related problem).

Are you running the latest video driver?
Do you have ALL XP updates installed?

I suppose nobody had this problem before? I am more than sure now that this problem is related to windows + driver of my video card. It's like windows suddenly forgets that I got my driver there. (nvidia)
Oh and sometimes in some specific games that have SSAO auto turned on my PC will actually BSOD with reference to n4_disp.dll i think or a file with a name close to that can't remember exactly. The BSOD doesn't happen while playing that game it happens exactly when I alt tab or exit the game. I didn't had this problem before and I downloaded a program called OCCT and I put my video card to a heavy series of test and it seems all works fine? I can still play a game after those tests (2h and then a 4h test) but most likely that will be the last game. OCCT also reported 0 errors till now in rendering frames. I don't know what else to say... I am not sure maybe I did it by mistake without realizing but I think at some point I installed Nvidia Omega Drivers and I wonder maybe I installed them on top of the default nvidia drivers which I guess is a very bad idea. So far I no longer have the omega drivers installed I did a full uninstallation of my drivers and it would seem that I couldn't install any driver anymore except through a program called Driver Genius. (windows kept popping-up an error stating my hardware is not compatible for the driver that I wish to install which is impossible since the driver I got when I bought the card was from nvidia and even newest version worked so far without any flaw until recently...)

I really want to avoid having to format my PC if possible. Any ideas?