general problems of the 2003 Subaru Impreza Wrx

I was driving to work this yesterday (2/12/04) morning, and was just crossing an intersection. I was going about 15mph, and saw the car in front of me hit there breaks. I pushed down the pedal, and to my horror, it seemed to go all the way to the floor without my car stopping at all. Next thing I knew, I had rear-ended a Buick (which as an aside suffered nothing worse than a scratched bumper, compared to my folded hood, ruining front bumper, and other twisted metal). I have about 15k miles on the car, and have not experienced this problem before. This is my first accident in almost 15 years of driving, and don't really know how to procede. I called my local Subaru dealer, who said he had no idea of such a problem. When the police officer was asking me what happened just after the accident, I describe the pedal to the floor for him, and hopefully he'll include my statement in the report.