Are you showing 100% CPU Utilization when this issue occurs? Do you see anything reported in the Summary of Administrative Events in Event Viewer at the time this happens? If you know exactly what time the problem occurred, you can also look at the System and Application Event Logs from that time back 1-2 hours and see if there are any Errors or Warnings reported that could point us in a troubleshooting direction.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT