Bitcoin client not starting on Windows XP

[Distribution]

I did the Windows update, and when I restarted the computer, my desktop background wouldn't display and Bitcoin wouldn't start. I did a system restore to before I did the updates, and now I still can't get Bitcoin to work (but my desktop is back to normal). Here is a picture of the errors in succession (top to bottom):
 

[Distribution]

I just tried again today, and I'm getting a different error: Error loading blkindex.dat.

[theymos]

See if deleting everything in the data directory other than wallet.dat helps.

[Distribution]

See if deleting everything in the data directory other than wallet.dat helps.

Are you a wizard? That worked perfectly.