Brake Electric Antilock problems of the 1999 GEO Prizm

I have complained about a loss of brakes several times with gm. This time, I managed to jerk the steering wheel around and a large log truckl missed me by inches. Gm cannot duplicate the problem, I have a vehicle I don't dare to drive anymore.

I have inconsistant, "intermitent" loss of brakes. 3 people have experienced this problem while driving the vehicle. The service departments at 2 different dealerships have been unable to duplicate the problem. The brakes will take at first, disappear for a couple of seconds, the pedal goes almost to the floor and the brake returns (so far). The loss happens in both cold/hot weather & wet/dry conditions without warning. I am told the car is 'safe' to drive, although I consider this problem 'unsafe'.