Just reinstalled the machine to windows 7 pro 64bit, and also installed the drivers and steam sdk.
Ive tried guiminer and this shows a few hundred khash/s and then locks up the whole of windows, surely this isnt right?
Does anyone have any ideas?
It looks like a hardware problem. You could try underclocking the video card to see if you can limp along that way. Have you tried using the cards "normally"? You know, in 3D mode? Run a benchmark or two? If it is indeed a hardware issue it's still not certain that it's the card, it could be a motherboard or PSU problem as well.