Ramjet555s responce is the only one out of 'undreds of replies of rubbish that I have read in the past week.
Unless RR has improved its powerplants exponentially the references to 45000,(FL450) is unavailable because at the weights that the 777 was at it would only get to FL390 near the end of its scheduled flight.
It used to be a very light 747 that got over FL370, untill there was only about 4hrs fuel left on board.
For my money the aircraft had a technical problem(breakup) or sever control problem at less than 5 hours out of KL.