Okay, I have two computers and two problems. The first I'll address here. My brother lent me his computer to do whatever I can to fix it. Compared to what I have, this thing's awesome.
From what I can tell, his computer has been jacked up by a virus. The computer starts up just fine, and the welcome screen appears. Then, I click a name. It reads "Loading your personalized settings..." and then flashes the desktop. After that, the desktop flashes off, the welcome screen appears again, and the name has "Logging off.../Saving your settings..." beneath it. Sometimes, the desktop doesn't even flash up.
Starting up with "Last known good settings" doesn't work, Safe mode does the same thing, and so I can't get into any of the restore utilities. The worst thing is, I have lost my Windows XP disk, and I don't think my brother has one. Any suggestions?