Really strange problem. I've never seen anything like it. Please help!

First things first I'm running XP, Asus mother board.

Ok so this is what happened. A power out caused my PC to turn off. When I booted it back up I was prompted to enter 'safe mode' or 'last know good config' etc. Sounds normal. So I tried 'last known good config'. The XP loading screen came up for a few seconds then it blue screened and automatically rebooted. Still sounds normal. I figured an important system file must have been corrupted or something along those lines.

Now this is where it gets a bit odd.

So in order to save some of my crap I pulled the hard drive out of my other working computer. Plugged it in (set it to boot from that hard drive) and booted up the computer. Yet again I was prompted with the choice of safe mode... etc. Which I thought was very strange seeing as its a completely different hard drive. I selected start windows normally and it did the same thing. Blue screened at the xp loading screen.

Next I unplugged the original hard drive so only the one from the other computer (the one that works) was plugged in. Started up the computer again. Same problem. I thought it could have been a problem with the mother board so i reset the bios. Tried again. Same thing.

I don't understand how this is possible. I'm yet to try the hard drive from the computer that doesn't work because the computer that DOES work doesn't have SATA plugs. But I can't see how it's the hard drive if i get the same problem when it's unplugged...

I really hope someone has encountered this before and can shed some light on the situation for me!

Thanks guys!

Just a couple of additional notes.
When I plugged the hard drive from the working computer back into it (the working computer) i was again prompted with safe mode... etc. but it worked.
Also it boots from cd no problem.