I was in Harpers Ferry WV last week and on a couple of mornings it was snowy/icy and the temperature was in the low teens. The first morning when I started the engine, after a few seconds I heard a rattling/vibrating/rumbling sound. At first I wasn't sure it was coming from my car because several other cars were starting up around me so I turned off the engine -- the noise stopped. When I turned it back on, the noise was back, but not as loud. I thought it might have been something like the wipers trying to move but were frozen, but I didn't have the wipers on. I can only hear in one ear so I'm not good at locating the source and direction of noise, but I felt the sound was more likely to be coming from the underside or outside rather than the engine, although I didn't feel any vibration in the seat. Anyway, after I finished cleaning the snow off the car, the noise seemed to have gone away completely and I drove off with no problems. 10 minutes later when I arrived at my destination, I tried to open my window to show my ID, but all the windows were still frozen shut -- that's how cold it was. At lunch time when I restarted the engine, I heard the noise again, but not as loud. It stopped as soon as I started driving. The noise was there again when I started up the next morning, but quickly went away. What do you think could be causing this? I am going to be out there again all week and I'm a little afraid about my car having a breakdown -- although the weather is not supposed to be as cold. I never had a problem during the winter last year, but I don't think it was ever that cold.