For the past week I cannot get sound on my MBA. It has all the latest software updates. In iTunes I see a Airplay icon and it points to my kids Apple TV's and also to my Airport Express which is only used to extend my Airport base station. In single mode it shows my computer but I cannot click it. In multiple it also shows my computer but cannot click to it. How do I disable this Airplay thing so I can get my sound back. It had sound one night and when I opened it the next day no sound. Thanks in advance.