Is the lockup still limited to BF3 in Campaign mode?
What Antivirus, AntiMalware, Firewall, or Remote Access software have you installed? If you uninstall McAfee Internet Security, does it change behavior? I'd recommend Microsoft Security Essentials for Antivirus.
Are there any Errors or Warnings in the System or Application Event logs? They may point to a troubleshooting direction.
It's possible you may have encountered a bug in BF3. I recommend posting in the BF3 forums to see if you could get some game-specific recommendations to resolve this issue.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT