Hi, my GE Profile microwave has started behaving weirdly. The problem is that it will intermittently shut off heating, cooling fan, turntable and light while the cooking timer continues to countdown and beep when finished. Earlier this evening I tested it a large cup of water and it paused for about 2 seconds, when I was about to push in the door it started right up before I could touch it. Any idea what I should be testing first and how???

Thank you so much for your help!