Did you try taking it to the dealership to have a look?
I'd recommend just buying an inexpensive memory stick and transferring your music to it rather than leaving your valuable ipod in the car (and it takes up less room in the armrest compartment)I tried other ipods and they work fine, mine has all the latest updates. There is obviously something going on with it though. I'm experimenting with a few things I noticed that were different with my itunes vs. other family members. Will try again in morn to see if it works.