I have a house guest who is probably one of the few teetotal geek folksinger freelance journalists in captivity.
The guest described to me a potentially useful feature of Tweetdeck that I didn't know existed (dividing people you follow into 'groups'), so I fired it up. (I don't use Twitter very often, life is too full already). It wanted to be synchronized and updated. Adobe Air wanted to be updated. I complied. The result was that all my Tweetdeck columns were blank – “no updates”. And I knew this wasn't true since the house guest was telling me of a recent Twitter post commenting on a visible feature of my family room.
Google to the rescue. It seems if you close all your Tweetdeck columns and then reopen them, all is well again. And so it was.