I thought driver sweeper wasn't a used piece of software anymore? The last I heard, we were told not to use it at all with windows 7...
Go through your device manager, and programs&features and make sure there are no drivers that don't belong. In fact, remove all display drivers and start fresh. Clean your registy, too. Avoid beta drivers, get only official drivers until everything is sorted.
What motherboard are you using? I can see what I know about its BIOS settings.