When you receive the message that "Windows Media Player was unable to load some of your files", the problem is usually caused by a corrupt installation of Windows Media Player.  MuvAudio will automatically try to re-register Windows Media Player to fix the issue.  Please restart MuvAudio after you receive this message to verify that the issue has been resolved.

If you still are having the issue, you can try updating Windows Media Player to the latest version or reinstall your current version from http://www.microsoft.com/windows/windowsmedia/download/AllDownloads.aspx