I had that problem too for a while. What happens sometimes is that if a song has a long title name on it - and many do - and when the file comes in, the '.mp3' file type association isn't at the end of the filename. If you have Mac OS 8.6 or 8.1, you have to put a filetype designator on it. Also, if you DO have the 'classic' mac OS running, may I suggest using SoundApp (just type it up in a search engine to find it) to listen to your songs with. It doesn't look like much, it's got no skins or anything fancy but it's a battlehorse that can handle almost any music file and it's super stable. Functional and plain, not pretty. You open it's playlist and drag the song icon into that, and it will automatically read the filetype and play it - unless you are going after something that's really popular, and it could very well be a bunk file. Lots of the more popular teenybopper stuff is deliberately corrupted, so there's always that. Gotta love the music industry for making new music so easy to discover. Riiight. SoundApp will tell you right off if it is playable. You can set it in it's 'preferences' to change the 'creator type' to sound app so whenever you want to listen to any music again, you just hit the song icons and it'll launch. The only thing I have seen that it doesn't handle are the proprietary Micro$oft file formats (.wma), and Apple's AAC .m4a format (which is just an .mp4 file. If you rename it, it will play with the latest version of QuickTime.)

Good luck.