Why are my brakes locking up? on 2002 Buick Rendezvous

After driving for about 3 miles, my brake pedal becomes hard and when i remove my foot from the gas pedal the car stops. After the car is parked for a day I'm able to drive again, but the same thing happens. My calipers, brake pads, rotors, and my mastor cylinder have been replaced already. Any help would be appreciated.

3 answers
how do cahange my own brakes, front and back ?
had same problem, come to find out a bad ABS sensor in the front hub, had to replace the hub
Sometimes the wrong brake fluid or oil in the brake fluid will cause this, Have a tech check this as its dangerous to have any brake problems that continues after a few miles