I get an BSOD with the code atikmdag.sys.?

I need a patch or a program to fix this global problem with ATI cards. Please ume for my sanity that yes, I've downloaded all manner of drivers from all manner of sites, a number of thrid party patches, and tried a number of workarounds. Nowhere else on the internet seems to have a clue. Thought I would try since my $800 is useless without a fix. Appreciate anything you can do.