I have a Golf TDi that I have owned for just over four years, my third Golf, all of which have been totally trouble free. I have never experienced this in any of them or any other car for that matter. Whilst parked on my drive the alarm activated two or three hours after dusk and for the next two evenings. I checked the windows, doors and closed the air vents just in case it was the wind that was doing it. I could not find the reason for the activations and when I reset the alarm it would activate one or two hours later. On the morning of the third day, sitting in the car baffled as to the cause, I put on the screen air vents on to clear the screen and up popped a moth. After removing the moth from the car, the alarm has been trouble free.