You could try a reset–hold the power switch down for 20-30 seconds plus–and/or reapplying the latest firmware–see the firmware upgrade sticky thread at the top of the forum.
Truthfully, though, I don’t have high hopes with either of these–my guess is that this is a hardware issue. If the above doesn’t work, I’d judt contact the seller, or SanDisk, for a replacement under the original sale or warranty (SanDisk is very good about this, as you already may know).
Good luck! And keep us posted–
