Our Microwave stopped working after three months.  It was bought new and installed into our kitchen right before we moved in.  We had no issues for the first three months until one day where it began to smell terrible and wouldn't heat anything.

Thankfully Frigidaire did provide a rebate for the microwave after a phone call or two.   Due to the fact that Frigidaire was easy to work with and we've had no problems with other appliances from them we replaced it with a similar Frigidaire microwave a few weeks ago.  So far, so good :).