1) reboot
2) open Task Manager-> Processes to see if a program is using your CPU heavily (CTRL-ALT-DEL)
3) Set a Restore Point, then rollback to your last restore point to see if the issue goes away (again, make a restore point BEFORE that so you can jump back)
4) Reinstall the VIDEO DRIVERS
5) Open Device Manager and see if a conflict or other error symbol shows up.