It may sound like a stupid question but can you think of when it started, was it after a new hardware or software install or did it just start out of the blue.
Another silly suggestion are you sure its hardware related, make sure your antivirus is up to date and run a scan, run MBAM and if Task Manager is unavailable after the event have it running on your desktop the whole time and when it locks up it should show cpu/memory usage at the time of lockup on screen.
Another silly suggestion are you sure its hardware related, make sure your antivirus is up to date and run a scan, run MBAM and if Task Manager is unavailable after the event have it running on your desktop the whole time and when it locks up it should show cpu/memory usage at the time of lockup on screen.