I am running into a very similar problem. I have an M3 player with v29 of the firmware.
I actually bought this from a friend and he had a bunch of games on there already. I added Elite Beat Agents and Children of Mana and when they load the loading bar comes up and then once it hits %100...
Nuh it was a joke, but I used to bite my nails when I was young, but when I started doing construction work and seen what crap was under my nails, I stopped.