Let's try again. There are really only three situations.

The door that the contestant first chooses has either (1) a car behind it or (2) a goat or (3) another goat giving him a 1/3 chance of getting the car. The remaining two doors then have (1) two goats, (2) a car and a goat or (3) a goat and a car. Monty opens one of these doors (with full knowledge of what is behind the doors) to reveal a goat. The remaining door then has either (1) a goat, (2) a car or (3) a car behind it. If the contestant switches to that door, he stands a 2/3 chance of getting the car.

Tell England I died trying.