Re:
Hello,
It's simple.
1. Go to Start > Control Panel > Add or Remove Programs...
2. Once the Add or Remove Programs window appears, check the box next to the option Show Updates at the top of the window...
3. Scroll down the list and click to select the entry Windows Media Player 11...it should be listed under Windows XP - Software Updates...
4. Next, click the Change/Remove button on the right.
Windows will roll back from Windows Media Player 11, to Windows Media Player 10.