Our microwave has been randomly giving us a message to "call for service," so about 2 weeks ago I called and had the service folks come out. The repair man was really nice and quickly said it was a loose wire in the control panel. He fixed the wire and was on his way. The microwave worked perfectly for about 5 days and then mysteriously started telling us to "call for service" again. A different person from the same company came out today to look at the microwave. Of course, it is like a car that needs service, it never acts up in front of the repair person. He couldn't make it recreate the error. He checked and tightened everything, put it all back together and tested it about 6 or 7 times. On test number 8, it decided it would only work for 3 seconds and then shut down. It did this several times in a row and then went back to working perfectly.
The repair man turned to me and asked if we have noticed any paranormal activity in our house or if it was built on some kind of sacred burial ground. Since the answer to both of those questions was no, he then determined our microwave must be possessed.
He decided to order a whole new control panel and that should take care of our crazy microwave. The microwave still works in the meantime, you just have to open and close the door from time to time to clear the message.