Why is new GE Spacemaker Microwave/ Convection oven whining loudly?

My new GE Spacemaker Microwave/ COnvection oven makes an unacceptable annoying "whining" sound (hurts my ears and makes me want to leave the room) heard in and across the kitchen when the device IS NOT IN USE. When the mocrovwave door is open, a moderately loud "buzzing" sound is heard inside the unit on the right side behind the control panel. These sounds are not heard in the sample in the store. The smart board has already been replaced 3 times. What can be done about this? Are there standards for unacceptable whining sounds and levels? I think this unit is a lemon and should be replaced by GE. They say it is normal.
Kit Miller
August 2004