Whatever the answer, it begs for more explanation, other than the age old All-American response of "Better safe than sorry".

Those of us with a bit of tenure remember when you could use your laptop on the ground, during takeoff and the climbout. We could get lots of work done those days. Then one day Northwest came along and started this new rule on no laptops until 10,000 foot. As the other airlines watch their planes continue to fall out of the sky while NW kept flying, they followed along.

The only SMALL rationale I MIGHT accept would be the danger of flying laptops in the event of an emergency. But then again, as someone pointed out once when reminded they should always wear clean undies in case you are in an accident. If you are in an accident (or emergency), you will probably $hit your pants anyways, so whats the point?