Brake Master Cylinder problems of the 2005 Saturn VUE

I was driving on a busy highway, braking regularly with the stop and go traffic, my brakes suddenly locked up on me and I was barely able to get back up to 50 mph. Eventually I was close to highway speeds, but the car wasn't shifting correctly. This happened a few times, and we began replacing parts on the brakes. Then, while driving again, the brakes locked down and stopped the vehicle. Once locked, the brakes did not release, or do not release completely. And we discovered - ultimately, once this happens you simply can't fix it. The first thing that we did is we replaced the brake pads, rotors, tie rod ends and boots, because we thought the pads were going bad and the rotor was warped (the front end had started having a shimmy at higher speeds sometimes also). That seemed to fix all but the shimmy so we then replaced the two front tires and had them rebalanced and realigned. After that the brakes suddenly locked up rather hard. I managed to get off the highway safely, but the vehicle would barely do 10 mph because of the brakes locking down. We took it in and replaced parts for all of the brake system. We replaced the pads, rotors, calipers, hoses, master cylinder and the abs unit (only found in junkyards now). Then the brakes locked once again and caught fire! we put it out, but this was a known problem, especially when attempting to replace brake parts on this model. We found numerous reports online that this was a common problem for this model, and not just for 2005.