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#11
Safe Mode is the solution for this sort of driver issues. A lot of fixes will work there, and if they don't you can always shut it off/remove it.
Try updating the drivers to the latest version from the nVidia website
Check the card to make sure that the fan is working
Check the card to make sure that dust/cat hair (my problem) isn't preventing air from circulating.
Try another video card to rule out issues with the card itself.