Thats weird, has the player been dropped etc recently?
The first thing to try would be a hard reset, there should be a small hole somewhere on the player that you can gently insert a straightened paper clip into until you hear/feel a click.
The second thing to try would be updating to the newest firmware (or reloading the firmware if you already have the latest version).
Beyond that I'm not sure what could be done. If neither of the above work, and the player is under warranty, I would send it in for replacement. My mildly educated guess would be that a physical connection has been compromised in the player, which is definately a manufacturer's defect (any shaking, dropping etc would wreck the hard drive long before it would damage sound solder points.)