[_Odyssey]

As i stated in your other post, you need to format the player.
I've just dealt with something similar in a friends player. Files kept corrupting and wouldn't play. Even though he was adding new copies of the files after deleting the old ones he found some of those wouldn't play. and each time he deleted and added mp3's he found he was losing space even though the number of files remained roughly the same. In Windows it said he had 930MB of files, but he really only had 315MB.
The fix was copying as much off the player and formatting it. Then copying the files back. It's worked fine ever since.