I remember when, learning to drive stick, people were like "if you're ever stalled on train tracks and the engine won't start, you can use the starter motor to move off the tracks."
Sounds a bit like that situation, except without the user input!
And I wonder if your model of car only applies parking brakes on rear wheels, while drive is on front wheels?
Forza Motorsport seems to have some settings bug on Windows. If I've had settings set to high or higher and turn them back down, performance never goes back up. Initial benchmark ran at a healthy 60-70 fps. Now, there's nothing I can do to get it over 24 fps - neither with full manual "low" across the entire board, nor with reset to default settings. Guess a future patch will solve it. #ForzaMotorsport#Turn10