GE Microwave Spacesaver shuts down and trips...

Question

Today our unit shutoff in the middle of a cooking cycle. It actually tripped the circuit. I reset circuit and tried to operate and it ran for about 5 seconds before tripping circuit again. I did notice that the fan did not seem to be operating and the units motor sound appeared much different (for this small amount of time) and the power lights dimmed just before shutting down. Lights, external fan/blower and clock work fine. Any ideas what problem might be?