I would guess the ones it sees are in mp3 format, with the rest being in mp4, which is Apples own format. You can check this on itunes. Itunes can also convert all your tracks to mp3 without much hassle. I cant remember offhand the exact way to do it but its on one of the options along the top. The only slight problem with this is that it copies the songs into mp3 format, so you end up with 2 of each, which then requires the deleting of the mp4 ones, which is a bit of a pain. Once done though you should be able to listen to all your songs. (Note, any purchased music from the itunes shop or anywhere else where the songs are protected will NOT play on Blue and me, and you get the message "protected media). I believe itunes now have a section of unprotected media to buy, as does play.com. If you need any more detail just ask and I will look when i get home