I've had my '02 for five days now, and it's been a really neat car. But this morning, I started the car and while I briefly fumbled with an MP3 player, the engine died. I restarted it, and the engine light came on, and on the informational display, it read "PS" and showed the battery symbol. The temperature outside was in the low 20s, and this was the first time I had started the car when it was that cold, if that matters. I made a short trip (2 mi), and when I restarted the car in five minutes, the same thing was on the display. Any ideas?