Ive got a 2001 Subaru outback wagon and I've got a potentially dangerous problem with the brakes. when i start it up on a cold morning (below freezing) it takes about a minute for the brakes to start working at their full potential. the brake pedal is very hard to push down, and the car doeskin want to stop, until about 1 minute of driving. after that they brakes work fine. any one know whats wrong and if it is still safe to drive?