Every once in a while, our microwave will trip the 20amp circuit breaker in our electircal panel. We can reset the breaker, and it will work again. When we start the microwave, it usually starts with a "normal" start up sound. Contrast that to sometimes it starts with a "hard" start up sound. By "hard" I mean it starts with a loud "thump" and then continues, vs. a "normal" sort of quit start up and then it proceeds to full power. Any help is appreciated. When it starts "hard" is when it will sometimes throw the breaker. But only occasionally....