I'd go with the crank sensor as well, my dodge ram did the exact same thing twice before I found the problem. I would be driving down the highway and it was like someone just shut off the ignition. Once it came to a stop I'd put it in park and hit the key and drive away.
Does the car have a tachometer? If so it will drop to 0 when this happens and read normally when it fires back up.
My 4 Runner did something similar a couple of weeks ago. Was coming in for a stop and it died. Would start up, but die when put into gear. Had to have the tranny serviced to get rid of metal buildup that was apparently screwing with things. It's run OK so far. But, if it happens again and needs a new transmission I'm getting a new vehicle. Not putting a new tranny in a 12 year old vehicle with over 150K on it.