Fiklefinger may have a point here. With a blocked Pitot Tube & increase in altitude IAS increases, to the point of "indicated overspeed", even though the aircrafts actual speed may remain constant. Many years ago a B727 crashed as a result of a stall brought on by the the crew increasing pitch to reduce the false overspeed warning. They had departed with the Pitot Heaters switched off. In a conventional aircraft an overspeed is dealt with by thrust reduction (partially) or deployment of speed brakes. However 1 of the options the control laws have, in the result of an overspeed is pitch up. Maybe the cmptr did what the 727 crew did before. I understand recently a 330/340 entered an overspeed, due turbulence on the Atlantic run. The aircraft pitched up, with a "severe vertical separisation issue" on an aircraft coming the other way, even though the AB crew were pushing column full forward!! Remember, all these events occure under severe stress for the confused crew. This, IMHO is a design flaw in the aircraft.
Jumbo.