I can confirm that by renaming that file my n900 didn't switch off. I've also seen in Power Statistics that when I plug the cable it says correctly "Charging" but even if the battery fills up it says always 0%.

I think that is why it randomly switches off, because it can't see the real percent of the battery. I can post some screens if it can be usefull to solve it.

O.T. any good "market" to install any apps? do the OS lacks of hw acceleration? Because I see a lot of skipping frames while playing a 144p video from youtube (using iceteasel browser).

Thanks a lot
BJ