Bixor

 was a planet that Duotheros sent the Sixth Doctor to in order to find out it's fate. It was destroyed because someone's trousers fell down, which lead to someone driving into a pylon which shut down a weapons manufacturer. This caused a set of circuits to be double printed which were placed in a guidance system which sent a misille into a faultline that exploaded the planet. (AUDIO: the Wings of a Butterfly)