I tried to run the Disk Cleanup accessory to free up some HD space; and then started having a few odd things happening with my computer. It would crash when I ran the accessory, and it gives me this error code:

***STOP: 0x0000007B (0xF78E4524, 0xC0000034, 0x00000000, 0x00000000)

I also now get warning notices from McAfee Security Center that there is a PUP or PRC on my computer. Neither sounds like a good thing.

I'd like to try to reformat the drive; though I'm not really sure how to do that. I tried booting with the OS CD (XP Professional Media Center); but it crashes with the same error code as above when it gets to the "starting windows" stage.

Any tips?

0x7B errors are typically caused installing incorrect device drivers when installing or upgrading storage adapter hardware, or a virus.

There are a lot better security solutions thasn McAfee but it is warning you that you are infected. I strongly suggest going to TechSpot's Security and the Web forum and read the stickies. Then follow the advice. if you are still having issues post them.