There is always the human factor when discussing the flight safety 'chain', the following struck me as a possibility after reading this thread over lunch:
Pilots are in the cockpit, flying into bad weather which for one reason or another, they have decided to fly through. They're IMC, at night, and presumably with frequent lightning flashes around them - the net result of which is zero visual references as to the attitude of the aircraft, the aircraft is also experiencing severe turbulence, which in turn reduces the pilot's ability to 'feel' what the aircraft is doing. Perhaps a single lightning strike hits the aircraft, not enough to cause catastrophic failure of the airframe but enough to cause the computers* to require a restart or whatever - this of course means the glass cockpit instruments in front of them are gone, which then means they are flying 'seat of the pants', only they can't without visual references or the feel of the aircraft.
It is worth pointing out now that it is not uncommon for pilots in these conditions to develop such things as 'the leans'; a condition where for whatever reason, when devoid of visual references the pilots intuition decided that 'up' is not where is should be thus causing severe disorientation (anyone who has flown in a manouvring aircraft in complete IMC will be know how disorienting it can be.)
So, what if when waiting for his glass cockpit to return, one of the pilots 'knows' that the aircraft is at the wrong attitude, and in his attempt to correct it, somehow either overstresses the airframe or flies his aircraft into the deck?
As far as a theory goes, it's just that, but as far as I can tell it does offer an explanation. Any thoughts?
*Whilst having some knowledge and experience of flying an aircraft, the exact systems of an A330 escape me, so I'm assuming something along these lines could happen?
(edit - I'm surprised civilian aircraft don't have to carry search and rescue beacons that activate on hitting the water and float?)