Not found, but I have a slight update on that one. I have been using a backup player in the car while my primary is being "enhanced". I find that I am no longer having the wake-up problem, and that it is going to sleep properly.

I suspect that it might be one of the first symptoms of the power source indicator leaf switch starting to fail. My guess at what is happening is that the switch is seeing bounce, and it is enough to trigger the player (with power being provided through the sled connector) to recognize a "change in power state" and boot.