It could possibly be an infected .vbs file. The best way to make sure the file is a true .mp3 file is to turn off the option to hide file extensions. In Explorer, go to Tools, then Folder Options, click the View tab, and make sure "Hide file extensions for known file types" is unchecked. Go through your folder where your MP3's are and if you see something like whatever.mp3.vbs then that is most likely a virus infected file.
