Hi there, Long-time mac user here - just took delivery of an 11" MacBook Air 2013. I've set everything up, but the messages app won't open - I just get a blank box and the only option available is to minimise it (photo attached). The majority of the options in the menu are also unavailable to click. I'm getting alerts when messages are received, but when I click them I just get back to this screen. I've restarted the app multiple times, restarted the macbook and have also removed and then re-added all of my accounts. All to no avail. Any help you're able to offer would be much appreciated. Thanks!