I downloaded Mountain Lion last night and at first everything was going smooth. I was able to use the Message application last night and it was working well; went to open up Messages again today and when it opened, but would not allow me to start a message, to someone it was working with the night prior. I turned off the computer for several hours, when I powered it back up and it wouldn't open, just this message pops up: Then I hit quit, and when I go to open it up again the same thing happens. Any suggestions??