I'm currently having to re-image my Windows XP desktop computer with the built in recovery software which is on another partition of the hard drive, with an image of the Windows XP SP1 installation that the computer came with, because when I booted up the system this morning, it'd get almost to the logon screen, but it would go no further than the Windows XP logo. (It would do the same even in Safe Mode.)
It's going to be fun having to install 1 million Windows Updates after this gets through.