I've never heard of this and have used P2P for a long time. Double check the extensions before downloading and make sure the sources and the file you are clicking on say mp3 and no other extension. you should also be able to check your settings to make sure that you are downloading only MP3 files if music is what you are after. Not sure what audio file extensions are these days. M3U sounds like a audio file to me and your player maynot recognize it as a music MP3 File. Its also good practice to check the size of the file you are downloading. MP3 files are usually compressed, while other extensions are not and are either larger or smaller. Hope this helps???