Disc error on MP4 player
After disconnected then reconnected your MP4 player to the USB port of a PC, the player displays "disc error" or "Device switching failed reconnect device please" when you put it on Music, Amv, Record, Voice, etc.. Windows may recognize but shows that the unit is not formatted.
To remedy this, download the HP USB Disk Storage Format Tool and format your drive to FAT (FAT16).
Link:
http://en.kioskea.net/telecharger/telecharger 127 hp usb disk storage format tool