Same thing happened to me tonite. First, when the microwave was done heating the food, the noise it makes to signal it was done was odd, and then there was the humming noise, which turned out to be the thing that drives the microwave plate to go around...it was going around still after the heating time was up. I eventually put 11 seconds on the timer and let it cycle (run) those 11 seconds, and then everything was back to normal. I live in an apt. building, so I guess I'll call maint. and see if anyone else has had similar problems. I was glad I'd gotten it to stop, as I doubt I'd have gotten anyone to come and check it out at 3:00 a.m.!