The Sears repair man who inspected our Kenmore microwave and contacted the factory to find out why it was overheating, said it was because we were using the high power setting for more than 12 minutes. There is no mention in the manual of a limited time that the unit can be used in the high power setting. There is no warning that the uint is going to shut down and when it does shut down, it doesn't come back on for 45 minutes to an hour.
Just Lucky, May 2012