While driving along and coming to a traffic light, my ML stalled..all the lights came on. The first time this happened, it re-started right away. The next time, the starter engaged, but the engine wouln't fire. After waiting about three hours, it started and ran normally. This happens only infrequently. No codes show. I have tried all my keys and have replaced all the batteries. I can drive it for a week with no problem and then it starts this crazy stuff again.