Just to be clear...

I am NOT suggesting that either of you are pressing the start/stop button or bumping the shifter into neutral while driving, as ABMW reported in the emergency stop thread.

I AM suggesting that the actions your X5 takes (on its own) are similar to what would happen IF you did press the start/stop button or bump the shifter into neutral while driving. IOW your X5 is doing one or both of these things all by itself. And one possible cause is an electrical fault due to faulty shifter controller, start/stop button, wiring harness or computer(s)/software glitch.

Funf Dreisig