Not at all computer-related, but my f(l)avourite
debugging story, ever.
I actually had something similar happen with my truck. Every time I stopped at a store in this one specific town next to mine, my truck would either start hard, or not start at all. It only happened at stores in that town, and I never had a problem anywhere else. My friends always joked that it must be something in the air that my truck didn't like. It turned out to be a faulty oil pressure sensor. When heading to that town, I always took the interstate, which heated up the oil in my truck and lowered the oil pressure. In addition to that, the town was built on a wetland, so all the stores have slanted parking lots from the massive amount of fill that had to be trucked in to make the land suitable for building. The grade was enough to drain the already low pressure oil out of the sensor, and trigger a "low oil pressure" condition that is designed to prevent the engine from running in the event that it is severely damaged in a crash. Apparently the computer doesn't record that error condition, since it would normally be observable from outside the truck.
I was finally able to replicate the problem (by accident) in my driveway when I had one side of the truck up on ramps.