I installed Avast (free version) yesterday for the first time. Now, when I receive an mp3 file in an email and try to play it with Windows Media Player, I receive the message, "Windows Media Player encountered a problem while playing the file." I get several of these each day from my voice mail provider and didn't have any trouble prior to installing Avast. Anyone have a similar problem? Anyone have any suggestions on fixing this problem? I'm using Windows 7 Professional. Plan to upgrade to Windows 10 at the end of the year.