Windows Media Player not detected

Try reinstalling Windows Media Player even if you know it is installed already. Sometimes simply installing WMP twice in quick succession will do the trick! After reinstalling Windows Media Player, restart your computer.

Make sure your installer is up to date and has not become corrupted during the download. You can get the latest version from Microsoft here: 

http://www.microsoft.com/windows/windowsmedia/download/AllDownloads.aspx