Hmm, sounds fairly similar to the problem I had, but it's hard to say if the way I fixed it would work on your player, since it's a totally different make.
When it happened to me, a bad file had somehow corrupted the player. Have a look in your manual and see if there's any mention of system tool type stuff... specifically an equivalent option to Scandisk that you'd find on a PC. If it's some sort of storage error, that should fix it. Then it'd just be a question of finding out which file knackered the player in the first place.
There's also the option of formatting the player, which is more drastic, and harder to fix.
And if you can't do any of those things, I suggest getting in touch with the manufacturer.
