I'm having the same problem for months, but since it was only with GBA games, and partly because I wasn't playing very often, I did't care.
But now, after 10+ hours of Final Fantasy IV gameplay I got a corrupted save, and everything was erased.
I noticed that this happens when I play the game, turn off and try to play after a day or more without having initialized the system. The backup thing somewhat fail and I lost the data.
Did anyone find a solution?
Sorry if I didn't make myself clear. English is not my first language, so don't blame me.
I was wondering how long did it take until your files start to get corrupted. I mean, is there an estimated/expected lifespan for these batteries? (If that's in fact the problem - and I do think it is).
My first save loss was FFVI for GBA, something like one year after I bought M3. Shortly after, I had one or two other GBA saves "mysteriously" erased.
Now, it's been half a year since the sad GBA facts, and any save backup seems to be "unstable".
Maybe the fact that I wasn't playing regularly contributed, but it's just a hypothesis. All I know is that now I'm afraid of starting any "new game". LoL