is it a grinding noise or does it sound like a fan?
It's sounds like a ticking timer on a board-game to me. My Husband and Son suspect that it's some kind of a timer arm that's not shutting off. It's only happening with the use of the Speedcook feature. You can cook with the Speedcook...it cooks fine but when done...that noise continues. Even once cooled.
We just plugged it back in again (tried several time today too) and this time it made a small similar noise and then it stopped. It won't do it again until we use the Speedcook feature again.
I feel it's whatever "timer" factor that is used when it switches back and forth between the Micowave and Halogen feature while using Speedcook. Thanks.