Siren.Kalilla said: »
It is either your graphics card overheating/wearing out or the drivers for your graphics card have become severely corrupted. If you have any kind of temperature monitoring software on your pc, load it and watch your GPU temp to see if it indeed is overheating.
Can be software related, because in safe-mode not all of your GPU drivers are loaded. Only the bare minimum required to give you a picture are loaded, thus the corrupted files are most likely not ever being used.
If your GPU temps are fine (most GPU's danger-zone is anything over 90C, but as high as 80C could cause that depending on the age of your card) then I'd re-download the newest drivers for your GPU and completely wipe all traces of your currently installed ones (easiest to do in safe-mode).
Edit~ Damn, I'm slow. Reading your last few posts, If it happens then happens again on reboot, it could be the fail-safes of the card activating again, but it's hard to tell at the moment. I want to say it is hardware related (like Serj said), but there is a slight possibility it is still software. When it happens and you go to reboot, does it happen again choosing a normal boot or does it happen if you chose safe-mode as well (During boot)?