BSOD Page Fault in Non-Paged Area AND IRQL DRIVER LESS OR NOT EQUAL

Hey guys,

This is my first post on this great website, but I've been on here for a few years now just getting some various info. I seem to have a very strange problem I can't solve, and would love some help. I'm working on a Gateway SX2801 small form factor PC for a relative. Not sure what happened before I got it, I believe some sort of virus,but my cousin had taken it apart for some reason. After not knowing what he was doing, he gave it to me in pieces. I put it all back together, but while installing windows 7, I get a BSOD. The BSOD is usually "Page Fault in Non-paged area" OR "IRQL Less or not equal." I did some researching, and tested the ram, hard drive and everything. I even bought a brand new motherboard, thinking it may be faulty. NO LUCK! I ram MEMTEST for 3-4 hours, no errors at all. It has 2x2gb DDR3. It seems to happen while "windows is expanding files." I've unplugged all the internal headers (USB, Speakers, etc) still no luck. Tried a different hard drive, still got the error. Unplugged the Disc drive and tried installing off a flash drive, still got the error. I've basically tried everything aside from installing a new PSU (I have a spare, but didnt think it would be the cause). I read something about changing the timing of the ram, but this bios/motherboard doesn't really seem to have anything like that. It may, but I don't see it. If anyone can offer some help, I'd really appreciate it. Keep in mind, I can not boot into Windows, this error is during the Windows installation. I'm sorry if this is posted in the wrong category, please let me know.

Dual Core Pentium
4GB DDR3 (2X2)
1.5TB Sata HDD
DVD/CD Burner
Built in memory card reader