[NEED HELP!!] G73SW freezes every few second like crazy!!

So let me begin this.
The time when I purchased this G73 a year ago was doing all fine, until two months ago, all the sudden it started to freeze every few second no matter what type of task I'm doing at the moment, watching video, playing games, even typing and moving cursor!! etc.
(For example, I play a video, everything seems fine and all the sudden, freezes for a second, then come back to normal...after 20-30 seconds, freezes again...)
Then I notice, the hard drive is reading something every few second, on and off with no stop. Reading duration usually takes a second to two second.
Here are some of my thoughts and observation:
1. Two months ago when freezes starting to happen, I'm pretty sure that during this time period I did not install any new program or new update.
2. This is definitely not CPU throttling. (I always have throttlestop open)
3. I have scanned with Kaspersky 2012 and GData 2012, no threats were found.
4. I have updated my Seagate XT firmware from SD22 to SD28, didn't solve the problem.
5. I have also alternate different Nvidia drivers but with no luck.
6. I've checked the health status of my hard drive with HDTune Pro, everything seems fine.
7. I download "Process Hacker" (I/O section) to find out which program is reading the hard drive consistently, and it turns out to be Asus Liveupdate, unfortunately when I terminate it, nothing happens.
8. Yesterday I recovered the whole system to factory setup using F9, the problem still persist!!
9. However here's something interesting, I had a Windows 8 Release Preview install on my secondary hard drive (it's also a Seagate XT), the problem no longer exist.

I'm kind of losing my patient now as it gets very annoying. If someone on the forum that is an expert could help me figure out the problem, I would be greatly appreciated!!

 

You have done a gr8 job troubleshooting, have you run any tests on your RAM such as Memtest86+ - Advanced Memory Diagnostic Tool ?
BTW once it is fixed I would remove or not install ASUS live update, it is know to be buggy, but obviously is not the cause of the freezing.

 

You're a Seagate XT owner running the SD28 firmware, so you should probably read this: http://forum.notebookreview.com/asu...65-seagate-momentus-xt-users-should-read.html. Sometimes the latest ain't the greatest... However, the OP of this thread ultimately replaced his Seagate XT with another one and believes a defective HDD may have been the true issue. He makes the point that SD26 may have initially resolved his issue because it eliminates the SSD portion of the hybrid drive.

Here's another post where the user resolved his lag issues while gaming by backrevving to SD26: Slow G73 jw - Page 2.

EDIT: I see you've come to the defective HDD conclusion in your post in http://forum.notebookreview.com/asus-gaming-notebook-forum/686989-gpu-stuttering.html.