When I try to shut down my MBP, I often get an error that the application Mail (version 2.1.1) did not quit properly. I then have to force quit before I'm able to shut down. Is there a way to resolve this?
In Mail, hit apple-0 or go to Window --> Activity Viewer to bring up the Activity Viewer, and leave it open while you try to shut down. Maybe Mail is hanging on something.