Microsoft is truly remarkable sometimes. If you apply Service Pack 1 to WinXP (which you better do if you want to patch critical security holes), the patch includes a fix to a buffer overflow in zip folders. Turns out that fix introduces a new bug that causes any zip folders to fail to extract any file that contains a comma in the file name. This bug was discovered over a year ago and Microsoft still hasn't provided a fix. If your system is a current, patched version of WinXP, you have this bug on your machine.
Zip folders are commonly used for backups and data transfers. Hundreds of thousands of people must have been impacted by this bug, but it goes unrepaired. I discovered this bug when I restored some of my files from a zipped backup folder and later noticed several critical ones were missing.
It's truly remarkable that these kinds of problems go uncorrected by Microsoft. But an internal Microsoft memo sent to Bill Gates makes it clear why: "There is a huge switching cost to using a different operating system. It is this switching cost that has given customers the patience to stick with Windows through all our mistakes, our buggy drivers, our high TCO, our lack of a sexy version at times... It would be so much work to move over that they hope we just improve Windows rather than force them to move."