@JSWolf: I had already tested the device database. That does not seem to be the problem. About sideloaded kepubs, yes it could be a posibility, but I've been always using them and I haven't suffered any issue. And if it were a "kepub" issue, am I the only one suffering it?
Nevertheless, some strange things happened yesterday (and just now):
- In several of the freeze/reboot cycles I got a "soft" factory reset. I mean I got a select-language dialogue when powering on and the kobo ini file has been deleted (the preferences has been reset, I've lost the fullscreen option and I've lost all Web Browser favorites). I've said a "soft" factory reset, because the Kobo account has not been deleted neither the sideloaded books. (So no more FullScreen mode as a possible trigger).
- I've suffered the issue even in "Sleeping", (I mean the book didn't turn on when opening my sleepcase) and even on "home screen"...
- Just a few minutes ago, my H2O even refused to boot. I mean after a long power button press the screen has blinked to white, the power led has stared blinking and... nothing more, it stayed in that state forever. It didn't even show the five progress squares. After a pin-hole button press it seems to be restored...
I think I'm going to perform a real FULL factory reset just in case, but I'm actually thinking there's something wrong in my H2O, (maybe faulty RAM?).
(Nice, it would be the second Kobo which self-destructs in three months, and I don't have news about my HD in repair yet...).