Laptop suddenly freezing and rebooting even after reformat

My Asus G73JH laptop [Windows 7 Home Premium 64 bit] is about 2.5 years old and the other day it began suddenly freezing and rebooting. What I mean by that is the following: A) When it freezes, there is no warning, no gradual slow down, no anything. The mouse instantly refuses to respond, the computer makes no "thinking" internal noises, nothing. I'm forced to hard reboot. B) When it reboots itself, it is also instantly. There is no gradual closing of programs, it's just SHABANG.

This became an issue suddenly. One day it was fine, the next it was doing this unpredictably.

So I decided to go ahead and reformat the thing and re-installed everything via the Asus-provided "AI Recovery Burner" program.

Annnd it's still having the same problems. Not only did I experience several errors when trying to do the million and one Windows updates, but it's still freezing and rebooting. Even in safe mode, it freezes. The timing of these things is unpredictable, it could happen 2 minutes after boot-up or, the computer could run fine for hours. So far, the freezing is much more common than the rebooting.

Assuming the issue was hardware related, I ran Memtest86 last night for 7 iterations and it turned up zero errors.

Please give me suggestions as to what could be wrong. Thanks in advance.

Please uninstall the following:

Code:

Start Menu\Programs\AVG	Public:Start Menu\Programs\AVG	Public
Start Menu\Programs\Catalyst Control Center	Public:Start Menu\Programs\Catalyst Control Center	Public

• AVG | Download tools and utilities

Run these tools & delete anything they find:

• Anti-rootkit utility TDSSKiller

ESET online scanner:

• Free Online Virus Scanner | ESET

Recommended antivirus program for Windows 7 based on stability compared to others:-

• Microsoft Security Essentials - Free Antivirus for Windows
• Microsoft Security Essentials Download | Free Spyware Protection
• Malwarebytes - The Free version
• Good and Free system security combination.

Do not start the free trial of Malware Bytes; remember to deselect that option when prompted.

Run a full scan with both (separately) once downloaded, installed and updated.

Run the System File Checker that scans the of all protected Windows 7 system files and replaces incorrect corrupted, changed/modified, or damaged versions with the correct versions if possible:

• SFC /SCANNOW Command - System File Checker

Run Disk Check on your hard disk for file system errors and bad sectors on it:

• Disk Check

Let us know the results.