ACKWARD shutdown sequence

So I've been having an issue that seems a bit persistent. Whenever I shutdown my G80, it seems to loose all power i.e. the music, the image of the car in the gate cluster will stop, and the seat will cease to retreat. If you try to start the vehicle it will not start. Should you open the door, then it's fine. This has been going on intermittently for well over a year. FWD to this past December and the vehicle went a step further, my wife made a quick run with the kids to school and day care, no issues, shut the car down, normal. Then she came home, shut it down went kn the house for a few minutes and re-started the vehicle, put it in reverse and the car no longer felt like working, it cut off leaving the gear selector stuck in reverse. Took it to the certified dealership and surprise, they cannot get the vehicle to reproduce the fault and I'm stuck with this beautifully crafted and designed hunk of...... I'll let you fill in the blank, any other folks out there with this or similar issues???