At 1325 mountain time, a Piper PA-24-260 encountered a near miss with a Beech 1900D when both attempted to land simultaneously on intersecting runways at Rock Springs-Sweetwater County Airport. The Piper was landing on runway 21 and the Beech was landing on runway 27. The pilot of the Comanche noticed the impending collision and attempted a go-around, but lost control and crashed. The Beech continued its landing roll uneventfully. No one was injured.