After I have had 3 issues in one and a half hour this morning, this afternoon I've been using it on battery (like this morning) for more than 3 hours without a single issue and I've tried everything to make it happen, no way, rock solid.
The only difference was that the battery level was lower and lower, I finished with 5%... therefore, if battery level matters, it is the opposite of what one would think: the more depleted the battery is, the better...
I don't know how reliable this is, but following what I was saying above, I can say that after fully recharging the battery another time, again today I had no hibernation issue.
The machine seems to "have healed herself": my guess is that the cause of the hibernation problem is the logic controlling the battery (this also because when plugged in or connected to the dock station the system never hibernates randomly).
Perhaps the battery was sending "confusing" messages to the firmware triggering hibernation. But, after fully discharging (down to 5% or less before recharging) and fully recharging it a few times (in my case at least 2 times) the logic controlling the li-ion
battery "resets" itself, overwrites some kind of erroneous parameter and stops sending those "confusing" messages.
Perhaps others could try this "cure" and see if my case can be confirmed. What I can say is that it's now 24 hours that I cannot get a random hibernation event, whatever I do, typing in Word, using Chrome, leaving the machine idling with several windows
open, leaving it idlind with the screen on for one hour or more... as I said, rock solid as if the problem had never existed.
And I did not change any parameter or setting: on battery, screen is off and sleep mode starts after 2 hours and the SP hibernates when closing the cover.