It is not a system graphics related problem. Then the entire display will become misfit on the monitor including the taskbar, start button and everything. That can be nicely dealt with in nvidia control panel using the adjust desktop size and position option. I believe it is a case of registry mess-up.
You should try to rollback the system to a restore point that is of much earlier than the problem is. If that also fail, a repair install never fails. System Restore Repair Install