Not sure if this is relevant, but when I picked up my new XF about a month ago in the sunny climes of Michigan, they had been suffering a severe cold spell for some time. My car had been sitting for about a year, unsold since it was built. I did the paperwork at the dealership and headed happily south.

I stopped for a bite after about an hour at a Wendys as it happened to be getting dark. Went back outside and the car refused to start. The dash lights flickered, then went dead. I surmised that the battery had gotten low and the below zero temps had damaged it.

I called for a tow service. When the guy arrived, he wanted to try a jump. He hooked up a heavy-duty cable and ran a current to my car for a few minutes. The car fired up easily then. He suggested that he follow me the few miles to the nearest Chrysler dealer so I could get it sorted out the next morning.

The headlights didn't want to come on. I fooled around with the switch (as cars were squeezing past in the Wendys lot), and got them on. Later, I realized I had turned on the fog lamps.

Next morning, the dealership made things right, but the service manager reported that both headlights were blown. I thought that odd since I had used them (I thought) to drive there the night before, but it was all a warranty repair, so I didn't complain. The high current jump must have blown the lamps (which weren't even turned on at the time).

I'm not suggesting you are jumping your car and blowing your lights, but think there must be some vulnerability in the circuitry that feeds theheadlights. It will take smarter minds than mine to confirm that, though.