After I updated to ML, opening Mail opened two identical windows. I closed one of them, then restarted Mail, and ended up with no windows. So then I used Window/Message Viewer to bring up the main Mail window, but now selecting an email doesn't display it in the viewer. It just says 'no message selected'. What's going on 
Edit: now can't quit Mail either. Quit is greyed out in the menu, and Command Q does nothing.
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Hmmm. I tried the Connection Doctor in Mail and it just hung altogether. So I force quit Mail, restarted it, and it was all working normally.
Edit: now can't quit Mail either. Quit is greyed out in the menu, and Command Q does nothing.
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Hmmm. I tried the Connection Doctor in Mail and it just hung altogether. So I force quit Mail, restarted it, and it was all working normally.