Strange system problems... is it hardware failure?

[sw0mgt]

The weirdest things have been happening.

I cleaned every component of my computer and re-seated the connections. I formatted and freshly installed Windows XP.

Sometimes I get into the following cycle:
1. Computer turns on for the first time
2. Goes to black screen straight away
3. Only way to fix the problem is to reset the CMOS jumper on the back
4. Flip the CMOS
5. Reboot -- runs great.
6. Restart or hard power off
7. Black screens right away
8. Must reset the CMOS jumper to get the screen to load

There have been a couple weeks where I had to go through this process every time I rebooted my computer.

Currently I'm having this problem:
1. Computer turns on
2. Loads windows
3. Black screens after Windows

I turn the computer off, boot into BIOS, change voltages and settings, and SOMETIMES I will get the system to boot into Windows. It will run beautifully for a few days! And then... black screens.

Sometimes the board black screens before POST, sometimes the screen freezes during the Windows loading screen, sometimes it black screens after Windows loads, sometimes it auto-restarts after Windows loads, sometimes it auto restarts before POST screen.

I get a lot of C1 errors, which are memory errors.

However, I ran my RAM through Memtest86+ for 11.5 hours and it had 0 errors. The system did not crash.

The system is stable when installing Windows XP from the CD. It has never crashed. And oddly enough, every time I do a fresh install, I can boot into the OS just fine! It'll run good for a few hours or days, and then more black screens.

It's like hardware failure because sometimes the board doesn't post or freezes during loading...
And it's like software conflict because reformatting and reinstalling Windows XP almost always allows me to boot into the OS at least a few times before more black screens.

We checked the PS. It is delivering the correct 5v and 12v when under load.

CPU problem? Motherboard problem? Motheboard/RAM incompatibility?

Help!

Intel Q6600
Abit IP35 Pro
Patriot Extreme Performance DDR2 800 RAM (2 sets of 2x1 GB)
Seagate 1000W Power Supply
EVGA GTS 8800

I've tried all sorts of voltages.

 

[sw0mgt]

Here's an earlier thread where I report one piece of the problem a year or two ago:

http://www.tomshardware.com/forum/forum2.php?config=tomshardwareus.inc&cat=30&post=292777&page=1&p=1&sondage=0&owntopic=1&trash=0&trash_post=0&print=0&numreponse=0&quote_only=0&new=0&nojs=0

Strangely, after that post, the system just started working, and was stable for about a year or so, until I recently decided to reformat my drive and re-install Windows XP. It's so bizarre how changing software brought on hardware problems.

 

[sw0mgt]

Here's another example of the weirdness that my system does. This just happened.

Reformat the hard-drive. Install Windows. Boots into Windows the first time wonderfully. I turn off the computer. I start the computer. Boots into Windows great again. I turn off the computer. Boot the computer. Goes into Windows a THIRD time! See how using a fresh install allows me to boot into the OS again? (I haven't been able to boot into the OS for days. A fresh re-start always fixes it... until something happens?!)

I boot into Windows the fourth time. Now my Ethernet card is acting funny. Before it wouldn't recognize the wireless signal even though it's sitting in the same place that it before when it recognized the signal for months. This time it recognizes the signal on the third boot-up. But on the fouth boot-up? Recognizes the signal but the task freezes when I try to connect to the network. Now I have no internet access.

I boot into BIOS. The only thing I change is the boot-up order. I add a DVD-ROM to boot in front of the Hard Drive. I save the changes and BIOS restarts. And now... black screens. (See how this suggests it's a hardware problem?)

This is wearing me down.