I've been using an 8800 GT since I built my computer in January 2008 and have had no problems. I haven't changed any hardware since then and I formated my single hard drive in mid to late September (which was the last time I installed the latest drivers).
This morning I tried to play the Left 4 Dead demo - before I got that far Steam told me I needed to update my graphics drivers to the latest version. I went to Nvidia's site, downloaded the 8 series Vista 64 bit (my OS) driver and installed. It unpacked and went through the installation as expected but then at the end said "The system has not been modified. To install the program at a later time, run the installation again.".
I tried installing again and this time it changed the resolution to 800x600 and came up with the same message. Device Manager doesn't recognise my card any more and has an "Unknown device" listed under "Other devices".
So what have I done and what should I do to fix it?
I wasn't sure what info would be needed so I'll just repeat that it's an 8800 GT card, Vista 64-bit, the previous drivers were whatever was the latest in mid to late September. The only possibly new piece of software I have is ESET Smart Security (previously had AVG) but I've tried disabling that and it doesn't seem to make a difference.
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