1) The lockup could result from a driver conflict. Antivirus, AntiMalware, Firewall, Remote Access, and Disk Management software are the usual suspects. What have you installed on your system?
2) Run CHKDSK C: /F /R from an elevated Command Prompt (right-click on the Command Prompt icon and choose "Run as Administrator" from the popup menu, then enter the command) to confirm your filesystem and disk media are sound.
3) Run memtest86+ to confirm your laptop's memory is sound.
4) Check the Windows System and Application Event Logs to see if they point to a troubleshooting direction.
5) You want to complete your troubleshooting while your laptop is still within your retailer's exchange/return period. If you are pressed for time, do an F9 ASUS Factory Restore and see if you can reproduce the lockup by installing as little additional software as possible. If you can, return your laptop to the retailer for an exchange. If not, watch carefully any software or updates you install to the laptop.
Running a Linux "LiveCD" distribution is an alternative method of troubleshooting if your lockup is caused by hardware or software. You just boot from the CD and try to reproduce the lockup. If you can, it is most likely hardware.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT