Front Air Bag Sensor Control problems of the 2005 Ford Explorer

2005 Ford Explorer, driving on a twisty coastal highway, about 35 mph, turned wheel to follow right hand turn in the road, there was no power to the steering wheel, or to the brakes. I had to wrench the wheel really hard to the right to keep from driving off of the road. I finally pulled to the side, turned on hazard lights, removed key from ignition. I reinserted key, car started and ran as if nothing ever happened. I drove for another 20 miles, about 40 minutes, without incident. Then the engine cut out again-no warning, just all of a sudden I was unable to accelerate. Service engine light came on, small wrench icon lit up, and digital display message "engine failsafe mode" appeared. There is nothing in the owner's manual about this warning message. I have taken the car to Ford dealer service where it was purchased. They have told me a sensor on a belt was damaged when the belt slipped off its pulley, and that sensor was therefore unable to sense the crankshaft, and therefore the engine shut down. There was no indication of why this occurred in the first place, or what measures could be done to assure that it does not happen again. This engine shutoff had occurred twice before, but both times the road was uncrowded, and straight, and the car ran fine after starting back up, so I didn't really think about it. But the idea that I could have very easily driven off the road, off a cliff (!) and died, or had my family in the car and this same thing could have happened, this to me is terrifying, and unacceptable. I realize there is inherent risk in driving a car, but potentially lethal malfunction of the vehicle should not be among those risks.