I'm no expert, but this used to happen to me regardless of temperature or time the unit was off. My car was sending a negative spike through the 12V line when the ignition was shut which was causing the empeg to shut down completely when the ignition was shut (no 30 sec. standby). Sometimes when I shut the car with the empeg in the docking cage, when I restarted the car, I would have to pull the empeg in and out to get it to turn on.
Since I installed the diode cable that Empeg sent, I am able to shut the car with the empeg docked and I haven't had to pull the empeg in and out to start it.
-Rob
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12GB MK2 Blue 090000736 (6166 in the queue)
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-Rob Riccardelli
80GB 16MB MK2 090000736