It might be a fragmented disk, if so, it will need to be re-formatted or replaced. This is the only solution I could think of.

I realize that this may seem silly but I deal with alot of Allen and Heath mixers and occasionally then lock up and need to be unplugged, wait a few minutes then replug them. This reboots the processor. Failing that I will dig into a reset proceedure for it.

I hope this helps,

Cheers,