This error occurs when there is an issue with the connection between your computer and our server. The most common time this happens is when you have been in the editing software for over an hour and it times out. However, I've heard of this issue if you are on a wireless connection that has a weak signal.
The only solution when you get this error is to back out and sign back in. I was able to publish one of your pages so it sounds like the connection may have timed out. Did you try closing out and going back in?