I use WMP 9x because of the copyright situation with the RIAA & Microsoft and its WMP10 BS. It could also be corrupted files as well. Check the files in Winamp Player if you have it to see if its corrupt or if its WMP10 blocking the file because of the copyright. You'll have to try to test the file in a different player to make sure its ok. You shouldnt have to do all that extra work to get the MP3s to play.