Well, the oven was off (in fact, it hadn't been used for many hours) and all of a sudden it starts emitting a high pitched whistle. We were in the dining room, and thought it was a smoke alarm in the house until we identified it as coming from the microwave. The digital display was completely bonkers with nonalphameric characters. The only way we could shut it off was to pull the plug on it. None of the buttons worked.
This happened several times and finally (after power cycling) we were able to get it to accept a new clock time, and behave itself. Never had any problems with this over over a decade.
Umm, is this a known failure mode? I'd figure that if the microprocessor goes south, the result would be less spectacular.
Whoops, there it goes again.
I gave the console a whack, and it stopped. Must be a loose card?