D'oh, still getting used to OSX menus after a year after 20 years on MS lol. Messages/Preferences accounts
I'm getting this at the moment. It has appeared on all my Macs, running Lion or ML that all have been logged in for months. I'm guessing iMessage is down at the moment. I'll give Apple some time.Apple have posted this http://support.apple.com/kb/ht5419