Bluetooth System problems with Sony Ericcson T608

I have a Sony Ericcson (SPRINT) T608 bluetooth phone. I am using it with my Prius 2004. I ran into a very strange problem.

When I plug the phone into the 12v power outlet in the center console, turn the phone on, and then the car, all goes well, the car finds the T608 and I can use it just fine.

However - if I LEAVE the phone on when I turn the car off, but it is still plugged into the 12v outlet - (yes I know the outlet goes dead), the system goes haywire. I can usually lock the car with the FOB, but when I get back, the FOB does not work. I have to open the car with the key. All I get is the two beep response. Also - the 12power outlet under the dash, and randomly the console, will STAY ON when the car is off?? Is that bizarre or what? I even have had the "trouble' light come on, then go off sometime later after a few car cycles. By the way, once the car starts, I can use the T608 and call out, however, until I unplug the phone from the outlet, and sometimes also turn the phone off even when disconnected, the problems will remain. The dealer is completely overcome.

Very wierd, but repeatable issue - I don't get it.!!