Like many people, I allow my Windows XP Professional box to download Automatic Updates from the Windows Update site. Over the last week, though, I've noticed that every time I reboot the computer, it downloads and installs the same update:
Security Update for Windows XP (KB835732)
Multiple security issues have been identified that could allow an attacker to compromise a computer running Windows and gain complete control over it. You can help protect your computer by installing this update from Microsoft. After you install this item, you may have to restart your computer.
It doesn't seem to matter whether I install the download or not, the next time the PC starts up, it downloads the update again.
[edit]This issue seems to have resolved when I updated that machine to Windows XP Service Pack 2 (beta) [/edit]