You described the steering "locking up" on your Focus. I expereinced the same thing, a power steering control failure that shut down the power steering. The car is at a dealer currently. The technician verified that the PSCM failed("failure code 3000" I believe) but hasn't been able to tell me why it happened. I can't trust driving this car again until the source of the problem has been identified.
Did you ever find out what caused the power steering failure on your daiughter's vehivcle? Perhaps it is the same issue I am experiencing.