Today I found that iMessage stopped working all of a sudden. I was receiving red exclamation marks on attempts to send messages from my Mavericks machine. It was working just fine a couple of days ago. I tried to sign out and then sign in but couldn't sign in after I have signed out. I then removed message-protected entry in Keychain Access and tried to log in again. The wheel is spinning for 20 minutes already. I'm at lost as what to do. Needless to say, the same is going with FaceTime. Is there anything that could be done? Reinstall from the scratch? Restore from a recent backup when it still worked? Any other ideas please?