On my GLK350, the ESP INOPERATIVE message pops up even when the weather and road conditions are warm, dry and clear. When it occurs, the car looses power/acceleration. Pressing the gas pedal would not speed up the car; it would after a while. So far, whenever it occurred I was lucky to be able to pull over the car, and turn off and on. After re-starting the car, the ESP INOPERATIVE message goes away and the car drives normally. This has happened on high speed expressway as well. It felt very dangerous and unsafe since a truck was following closely behind. Fortunately, I was in the outer lane and was able to move over on the shoulder. Has anyone experienced the same safety issue? What was the diagnosis and how was it repaired?