Prior to downloading WMP, make sure you have no older versions on your system.
After installing WMP, you must increase it's
preferred memory between 200%-300% (depending on how much real RAM you have).
http://docs.info.apple.com/article.html?artnum=18278 Mac OS: Assigning More Memory to an Application Program.
The same directions are also in the
OS Mac Help Menu.
Then you must rebuild your desktop. Use
Techtool Lite or
Trash*Desktop (TD may delete Finder comments )to rebuild your desktop w/extensions off. Does a better job than manually & you avoid all the finger gymnatics. You just have to hold down the
shift key to shut off extensions.
Restart to turn the extensions back on again.
If you want to rebuild manually, see KB article
http://docs.info.apple.com/article.html?artnum=10182 Rebuilding Desktop File and Icon Recovery.
Good luck