I saw a show on the Hitler (excuse me, History) Channel that speculated that TWA 800 could have been downed by interference from an AWACS. At least I think the other plane was an AWACS. It was a military plane, however. Something about the instruments on the AWACS that caused interference to electronics that passed through its flight path. Somehow I doubt we'll ever know the true story.
edit - I added these links:
http://www.holology.com/twa800.html
http://www.physics.ohio-state.edu/~w...twa800-emi.htm
Did the other two planes take off from the US? Because it is US airport security I am wondering about.