Others have had a problem with one of the wiring harnesses that goes through the radiator support (I think) rubbing against the metal and exposing a couple of wires thus creating a short. The fact that it won't start in neutral any more makes me wonder if it's the ignition interrupt switch. I've never tried to start mine in neutral so I don't know how it would work, but in Park there is a little solenoid/switch that allows you to shift out of park only if you depress the brake pedal. If the VX is running, and the radio is off or down, you can actually hear the switch click when you step on the brake pedal.

That's my WAG (Wild ***** Guess).