The memory chips inside may need re-formating. Plug your MP3 player into your computer. Go to my computer, and right click on your MP3 player's disk drive icon. Click format. Accept the default settings and click format again. Note make sure all your music files are backed up (if this is possible) as this erases everything on the drive and cleans it up, reseting it almost to factory defaults.
Dr Joshun, March 2009