I just updated to the latest 0.51 stable. Before playing, I launched FRAPS and decided to get a little more serious about raising my frame rate. I turned clouds down, disabled ambient occlusion, etc., etc. and then launched the game.
I spawned, took about six steps and then I got a popup that says "Confirmation of Changes ... Authentication Timeout." When I click the "Continue" button it takes me back to the main menu. So, I click "Play" ... "Spawning in 59 seconds ..." spawn and then in about thirty seconds, whether I move, or not I get a popup that says "Confirmation of Changes ... Authentication Timeout."
Sometimes, just before I spawn I get the popup that says "Confirmation of Changes ... Authentication Timeout."
I initially made about four, or five changes to my configuration, but I have made about fifteen trips around this loop.