G E Microwave works but will not heat.

G E Microwave over the range model JVM6175

It is only 4 years old and only 2 people in the household. Sometimes after we cook on the stove below the microwave oven and then we try to use the microwave it runs but will not heat. It remains like that for a few days and on the second or third day after that it works and heats like normal. It will operate normally most of the time. It may happen at least every month or so. And yes when we use the stove below the microwave oven we always use the vent fan which is vented outside of our highrise condo.

Any suggestions.