Oct 6, 2009
This might happens because of the recent WMP updates if any or file corruption due to non microsoft software installation

To resolve this :

1. Click Start -> Type CMD on the “Start Search”
2. Right click on CMD and click Run as Administrator
3. Type unregmp2.exe /SwapTo:32 on the command prompt and hit enter key
4. Close the command prompt and reboot the computer

You should be able to open up Windows Media Player without any error. If the above steps didnt work then..

Click Start -> Run -> Regedit -> Ok
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MediaPlayer\Setup\\wmplayer.exe and delete wmplayer.exe

Post back with your findings!