Coming home yesterday, the brakes worked properly for a few miles, then at the next stop, the brake peddle went almost to floor with hardly any stopping power, had to use emergency brake to help stop. I continued home (very carefully) with this situation happening at every stop until almost home when the brakes started working properly. Now with the car parked, the peddle is hard, both with engine on and when not on. The fluid reservoir is full and the ABS brake problem light did not come on during the trip home. Anyone have any ideas what may be going on?

Thanks, James