I saw something about the fuel switch too. But, from what I heard they had already tested one solid fuel booster before. On the other hand, the news was coming in slowly and without much background. Remember that's what happened to Challenger. The O-rings had blow-by in the cold air and cooked the outside of the rocket engine. Liquid fuel seems safer most of the time, but the catalysts are usually poisonous chemicals that are very, very easy to oxidize (and thus, 'splode') as well.

Either way... this is a sad turn of events. One expects there to be dangerous problems in a space program, but not so quickly into a commercial side.