BSOD on every boot. Can't Safe Mode or Recovery

Found this great forum while scouring Google for some help because I'm frankly not that familiar with Windows 7. Also, this isn't a computer that I used, so I'm not familiar with what exactly was happening, if anything, before the situation it's in now.

My friend has the following system:

Gateway NV7915u
Intel Core i3 330M 2.13Ghz
500 GB SATA HDD
4 GB DDR3 SDRAM

Windows 7 Home Premium 64 Bit

On Start Windows Normally, it just freezes on "Starting Windows" I have left it like this for days with no progress.

On Launch Startup Repair, "Windows is loading files..." OK Then when "Starting Windows" appears, BSOD:
DRIVE_IRQL_NOT_LESS_OR_EQUAL
STOP: 0x000000D1

On Safe Mode, BSOD at classpnp.sys:
PAGE_FAULT_IN_NONPAGED_AREA
STOP: 0x00000050

On Debug Kernel, freezes on "Starting Windows"

On Windows Home Premium 64-Bit Recovery Disc (I downloaded this, I did not make it from this system, the owner never did this), Windows Setup [EMS Enabled].... "Windows is loading files..." OK, Progress bar moves a bit and then:
STOP: c00021a {Fatal System Error}
The initial session process or system process terminated unexpectedly with a status of 0x00000000
The system has been shut down.

If I use a Retail Windows 7 Disc, "Windows is loading files" OK, then "Starting Windows" the logo forms, and boom:

STOP: 0x0000008E

I took the HDD out of this system and popped it in my tower. I ran a virus scan (as expected, nothing found), ran an Advanced System Care 5 scan/cleanup. Then I ran a Check Disk (Checked - Automatically fix file system errors and Checked Scan for and attempt recovery of bad sectors), finished fine. no issues.

All files are accessible and everything seems fine on the HDD when it's a slave in my tower.

So at this point, since I cannot boot into any form of Windows or repair or command prompt that I am aware of, what can I do?

Is there a way to repair the OS or whatever could be wrong on the HDD when it's a slave on another system?

The other system I plug the HDD into is running XP.

Thanks in advance for any help, I appreciate it.

Have just read through your post on behalf of your friend & noted

...ran an Advanced System Care 5 scan/cleanup.

Current accepted wisdom with Win 7 is to NOT use a cleaner.

Just a FYI.

If you ever think your Registry needs to be cleaned, repaired, boosted, tuned-up, cured, tweaked, fixed, or optimized it shouldn't.

In other words, injudicious use of "Registry cleaners" CAN & DOES cause problems.

IMO - there is no reliable way for a third party program to know whether any particular key is invalid, redundant or neither.
Some registry cleaners may not know for sure whether a key is still being used by Windows or what detrimental effects removing it may have.
This has led to examples of registry cleaners causing loss of functionality and/or system instability.

Should you decide to go ahead -
Make sure you have
1.a current System Restore point created.
2.a recent "Back up" of your computer- preferably to an external HD.

Just wanted to let everyone know I resolved the issue.

For whatever reason, I didn't run Memtest. After running it, one of the sticks was throwing a ton of faults. Figured out which one it was and voila.