I got the new firmware update so I closed down all applications and pressed the provided shutdown button. BUT there was apparently a "Choose a folder" dialog box from Dropbox app open and not visible until now! wtf? And now my macbook won't shut down, it just sits there with the Choose window greyed out and the rotating "loading" animation below. What should I do? Is it safe to turn it off with the button even though it said DO NOT SHUT DOWN? I thought I read it would start installing after you press the power button again.