What Antivirus, AntiMalware, and Firewall software have you installed to your G74SX?
If you UNcheck everything in the "Startup" tab of MSCONFIG.EXE
except:Realtek HD Audio Manager
Finger sensing Pad
QuickGesture (both 32 and 64-bit)
ATKOSD2
ATK Media
ATK Hotkey
Windows (R) Win 7 DDK driver
does the system boot up and run stable?
Are there any Warnings or Errors in the System or Application Event Logs that point to a troubleshooting direction?
ASUS WebStorage has been implicated in EXPLORER.EXE crashes. Disable it or uninstall it to see if the lockup is resolved.
Consider the Brody Stability Principle, which states that system stability is inversely proportional to the number of ASUS applications installed and uninstall all ASUS apps with the exception of the ATK Package.
If these fail to produce a stable system, consider contacting NewEgg and exchanging your G74SX for a new unit.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT