go in in SAFE MODE, go to device manager, and check that you don't have like 5 diff displays and\or monitors in the list. Also check while you are there under disks, cdrom, etc for duplicate\wrong entries. Remove whatever is not right. If there are multiple
display\monitors, I would remove all of them and let windows put them back in right.
You have to do it in SafeMode cuz in regular mode you won't see a lot of stuff.