The brake pedal is directly attached to the brake booster. If the pedal won't move, I would think the booster is not allowing it to move. Could there be water in/around the booster that froze? Maybe a major malfunction in the booster or linkage with the pedal?

There is no pressure getting to the lines. It sounds like it's something between the pedal and the booster, not further on. The ABS could certainly cause problems, but the pedal should go to the floor.

I'm just guessing here. I'm hoping it's something frozen, cuz' it was wicked cold up your way.

Mark