Method 1: Uninstall Windows Media Player in safe mode for XP
Start the computer in safe mode. To do this, follow these steps:
Restart the computer.
Press F8 while the computer is restarting.
Click Safe Mode, and the press ENTER.
Click Start, click Run, type appwiz.cpl, and then click OK.
Click Windows Media Player 11, and then click Remove.
Follow the prompts to uninstall Windows Media Player 11, and then restart the computer when you are prompted.
If Windows Media Player 11 is not removed, try Method 2.
Method 2: Run a program to remove Windows Media Player.
If Method 1 does not work, you can use this procedure to uninstall the core of Windows Media Player.
Click Start, click Run, type %windir%\$ntUninstallwmp11$\spuninst\spuninst.exe, and then click OK.
Click Next, and then click Finish.
MS link
here for XP.
Link
HERE for using a dedicated Uninstaller. Other Uninstallers are available.
THIS one is probably worth a look at.