general problems of the 2001 Mercedes Benz S430

Happened twice in one day while traveling at a speed of approximately 50-60 mph. The first time happened as I was driving on a service road traveling at about 50 mph. The second time happened as I was traveling at approximately the 60 mph. Both occasions the front brakes abruptly and completely locked and forcefully pulled the steering to the right. Each event was were in the movement of a lot of traffic, during rush hour. I was unable to accelerate, the brakes resisted slowly pulled the car to a complete stop. While traveling in the right lane I had to cut the vehicle completely off. The vehicles around were forced to stop abruptly and the other cars began honking. I had to turn the car off to reset. I had three minors in the vehicle and was picking up another one of my sons. The second instance was about 30 minutes later while traveling on highway 30, on my way home after picking up my son, so now I have 4 minors in the vehicle. The second time in the middle lane traveling at a speed of 65 mph. Although I was able to make it to the right shoulder and was fortunate to not get into an accident with any other vehicles, and the road conditions were clear, it was at night and extremely dangerous and life threatening for everyone driving around me and invading myself while being on the road. I took it to the dealership the next morning and there inspection suggests that they are unable to duplicate the concern and the mechanic stated "found no relevant faults" to this vehicle.