I'd be tempted to boot up a Linux "LiveCD" distribution and attempt to reproduce the problem to confirm it's hardware-related. If the issue does not occur, boot back into Windows and run SFC /scannow to replace any corrupt Windows system files. If that fails, reinstall Windows.
Of course if you CAN reproduce the issue in Linux, it confirms a hardware problem and you'll need to send the laptop in for repair.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT