display driver error HELP!!

Hi,
Ever since I built my computer, I have had problems with the "Display driver nvdkllm, (or something like that) has stoppped working and successfully recovered" error. I used to get it constantly with my 8600GT, along with weird colours popping up and tearing, and BSODS. Nvida support said I had a faulty card, thought removing it and scrubbing the drivers didn't help. I re-installed windows without the 8600GT and had no immediate problems. To test, I put it in again, and hello, problems straight away. I chucked the card and re-installed windows again.

I needed a new graphics card, so a Palit HD4870 was ordered. In the meantime, on integrated graphics, none of my games would start due to minimum requirements. I managed to play some old timers, but I got bored fairly quick. I thought I would try a game of vista's 3D chess. but then to my absolute horror, the nightmare error returned. The screen went black for a second, and then the dreaded error; "Display driver (intel _ _ _) has stopped working and successfully recovered."

I also experienced a BSOD on start up, a problem that used to plauge me that I thought I had chucked out with the 8600.

So now it seems, that with this problem on two different graphics cards, (and doubtlessly I will get it with my HD4870), It is not a driver issue (I installed all of the latest nvida drivers on my old card), or an issue with the Graphics Card, but an Issue with something else.

So any help would be very welcome, I have been looking forward to finally having a working PC with enough grunt for modern games, but alas, it seems there is still more struggles to go.