Latest WMP 10 Security Update on Windows Update breaks media playe

I check Windows Update every week, and install all the critical updates. This
week, I downloaded, and installed, the Windows Media Player 10 Security
update. Later the same day, I attempted to play both an WMA, and an AVI
movie. Instead of playing, I received this error message:

The filw wmp.dll has a version number of 10.0.0.3990 where 10.0.0.3802 was
expected. Windows Media Player is not installed properly and must be
reinstalled. Do you want to install the Player from the Microsoft web site?
Y/N

The files I was unable to play, did play properly before installing the
update.

I downloaded, and reinstalled WMP 10. Afterwards, I was able to play these
files. I went back to Windows Update, downloaded and installed the security
update, and promptly got the above error message.