If the files that you have transferred were purchased and downloaded from the Internet, check with your content provider to see if the files are subject to playback restrictions (Digital Right Management). Your Key Ring Audio player cannot playback these files. * You may have formatted your Key Ring Audio player with Windows Explorer in a wrong file system. Reformat your Key ring audio player again by going over the steps below. 1. Hook up the player to your PC. 2. Open Windows Explorer, select your Key Ring Audio player labeled as removable drive and then right click to select format. 3. Under file system select either FAT, FAT12, FAT 16 or FAT32. 4. Click START to format the player.