XP not booting, now with new clues

Ok, I've been having issues with XP Pro with SP2 not booting. Anytime I hard restart (press the button) it gets past the logo loading screen, then hangs with a black screen. I got it to work once by flashing the BIOS, but after that it kept doing it.
XP also hangs randomly, and it doesn't seem to matter what I'm doing. I can be in a game, surfing the Internet, or just be letting it sit at the desktop. I can move my cursor, but nothing is clickable. If I shut it off with the power button and let it sit for about half an hour, it'll boot up and work fine until it decides to freeze again.

I did notice that when booting in safe mode it freezes after loading mup.sys. I've seen a billion threads with a billion different solutions. I tried reseating PCI/USB devices and reinstalling drivers, no luck. I'm trying to run the Recovery Console on an XP CD, but either it takes forever to examine a 160GB hard drive (the HDD LED has been solid on for about 15 minutes) or it's hung. I've also read that many people tried reformatting with no luck. I did try loading default BIOS settings and using "Last Known Good Configuration" in the XP boot options...still nothing.

Any clues? All I know is that it freezes on mup.sys (was giveio.sys, then I uninstalled SpeedFan and the GIVEIO service). If I get the thing to boot properly I can say whether I still have an "Unknown PCI Device" listed in Device Manager.

 

Ok, it's just getting weirder now. Just for everyone's reference I have a M2N32-SLI Deluxe Wireless mobo, which has a Phoenix Award BIOS.

Here's what happened:

-booted off the recovery CD that came with the computer (just installs XP and manages partitions) and deleted a partition on the XP drive that had Vista. The boot menu still comes up, though, and I should've waited until I could boot to use partition software to delete it that way instead. How do I get it so the system recognizes that I only have one OS now, since it still thinks I have Vista installed?

-ran the Recovery Console by booting off an XP CD I had, and typed "disable mup", but still hung on "giveio.sys" and loaded "speedfan.sys", neither of which exist

-noticed my second non-OS hard drive wasn't being detected, so I checked the connectors, rebooted, is now detected with the other accurate information. When I open a Windows Explorer window and access it, though, the system freezes. I haven't tried accessing the OS hard drive to see whether it's an Explorer issue or not, or if the system just felt like freezing again.

-unplugged, waited half an hour, plugged in, unplugged USB mouse booted fine, plugged in mouse, deleted all "speedfan.sys" and "giveio.sys" registry entries

-restarted, tried running in safe mode, now hangs on "SiRemFil.sys" (if I disable that I'm sure it'll hang on some other sys file, probably the one before it)

So basically I haven't gotten anywhere in terms of making it boot properly all the time, or keeping Windows from hanging randomly. All I managed to do was screw up the boot menu and allocated space on my OS drive and somehow manage not to access the second hard drive right, and get rid of invalid registry entries.

I keep reading that it could be a USB problem (the most prominent of a zillion other things), but I don't know where to start. Maybe I can try unplugging the connectors to the front panel, but that probably wouldn't help with it not booting right. I never had this problem until I brought my computer home from school, and I hadn't changed anything when it started happening. I had done a virus/spyware scan right before I brought it home, so that's not an issue.

 

Have you tried disabling usb in the bios? one thing i would try would be to reload xp and do a full erase - zero out the hard drive. maybe create a new xp cd with drivers for everything already slipstreamed (im assuming since you've slipstreamed sp2 you know how to do this). also before you do that unplug the front usb ports and see if the back are functioning properly. Have you checked device manager to see if there are any conflicts with drivers or missing drivers?
Just throwing out ideas for you try the least drastic first - i hate having to reload all of my software. also with the hard drive problem try going into its location settings in the bios (ex. primary master slave master etc.) and fooling around with it and trying different settings (worked for me when i tried to put four hard drives into a single tower on ide's).

 

Ok, so far everything's working fine. I moved the motherboard SATA plug to another spot, and now my second hard drive is detected and working fine. I also found out about the fixboot command in the Recovery Console, and after using that to make a new boot sector, the boot menu no longer appears. I used a partition manager to reallocate the extra space so it's used by the first (and only) partition. I boot up, everything's perfectly fine. No issues to speak of so far. I haven't tried hard resetting, but I don't dare try it unless I have to at this point.

BTW, the main freezing issue I was having was while playing Oblivion for about 20 minutes (this only happened recently, after having played it for almost a year flawlessly), so I'm thinking it's either the graphics drivers or the game itself. First I'll reinstall the game (I heavily tweaked and modded it, that might have caused an issue), then reinstall older graphics drivers if freezing persists. I've only played one other game (NFS Carbon), and it's worked fine, so I'm guessing it's just Oblivion.

I also unplugged my 12 in 1 reader, but I'll try plugging it back in (the mobo ADH connector) at some point and see if that was a potential source of the problem. The drives might still be listed as a "USB Mass Storage Device" though, which would be weird.

I still have an "Unknown PCI Device" in the Device Manager, though, although it doesn't seem to be causing any problems. My two PCI devices are a modem and sound card, and they both work perfectly fine. I try disabling it, and Plug n Play just redetects it and tells me to install drivers. I could disable Plug n Play, but I'd probably forget to re-enable it later. I reseated both devices, and that didn't help. I want to guess the front panel, but that has nothing to do with mobo slots, just a couple plugs right beside the ADH connector.