BSOD as Windows starts - Different code each time, can't reinstall/rep

I apologize for the length of my post, but I'm going to try to be as descriptive as possible. This is my first home-built machine, so I don't have the safety net of a tech support plan and am pretty baffled.

Background: I wasn't even using my computer when this problem started. I noticed the BSOD from across the room. I had installed Box.com's new syncing software earlier in the day. After installing it, Windows Explorer crashed a lot, so I ran a system restore to the point before I installed it. I also had some funniness where MSE asked to be validated again -- I think that was before I ran the system restore.

Current situation: When I boot up my computer, I'm given a choice to run something called Startup Repair or to try starting up normally. If I choose Startup Repair, Windows begins to load files, but I get a BSOD before it's finished. If I choose to start up normally, shortly after the Windows splash screen appears (but before the colorful animation begins), I get a BSOD that quickly disappears as the computer reboots automatically (I don't know how to stop this). This will happen repeatedly if I keep telling it to start normally.

BSOD code: I seem to get a different one each time. The most common one is 0x0000007E, but I also see 0x00000050, 0x00000019, 0x0000000A and others.

Things I've tried already:
- I removed one stick of memory, still got BSOD. Replaced it with the other stick of memory, got the same result.
- I tried using the Windows 7 CD to do a repair (or even reinstallation as I'm getting desperate), but I always get a BSOD while Windows is loading the necessary files (the part with that DOS-like status bar at the bottom).
- I can't seem to enter Safe Mode. I hit F8 at startup, and instead of the Safe Mode menu, I'm given a popup (I think it's from my ASUS motherboard) asking me which drive I want to boot from. No matter what I choose, I'm never given the choice to boot into Safe Mode.
- I unplugged the machine and held down the power button for 30 seconds (saw this suggested somewhere) until the light on my motherboard went out. Then I tried restarting it, but nothing was different. I'm still confronted with the Startup Repair choice again.

I'm at a loss. Under the circumstances, I don't know how to produce logs for you guys to look at. Even if I wanted to just give up and format/install fresh, I can't do that either. Things I'm reading seem to indicate this is a memory thing, but I don't have any spare DDR3s to test out. Could this be my motherboard? Is there any way to tell?

My system specs are in my profile.

Thanks in advance!!

Edit: Sorry, I didn't see those BSOD posting instructions until after I posted this. I'll go take a look at those now and amend this post when I'm done.

Edit #2: Ok nevermind. I can't even access Windows, so I don't think I can run the SF Diagnostic Tool at all.

Today I figured out how to get to the Safe Mode menu. But when I select Safe Mode with Networking, I get a BSOD and the computer quickly reboots (too fast for me to see the BSOD code).

Anyone have any ideas what this could be? Does this sound like a faulty motherboard? This doesn't seem like a HDD issue, but I'm not an expert.

I got another update for you.

I cleared the CMOS, but that didn't help anything.

I found a system recovery disc I created when I first installed Windows 7. Unfortunately, that wouldn't load either. I get a BSOD as usually once the files are loaded.

I do have an old Windows XP SP3 install disc, so I gave that a try. To my surprise, it was able to load all the files and pull up the first screen of the install. But I don't want to load Windows XP on my machine, so I quit out of the program.

Updated the BIOS, but still no go.

Well, I didn't get any responses, but I thought I'd update this thread anyway in case someone has a similar problem. Turns out the problem was with my processor. AMD replaced it with a new one and everything's working fine. Unfortunately, my initial guess was that it was a motherboard problem, so I wasted a lot of time sending it in, getting it repaired, and getting it shipped back.