When you use the refresh button option, it repeats the last function the browser did, which, in this case is a piece move. Because you can't move twice, or repeat that action , you get an error message.
You will notice, that if you go to the game, without making any moves, you can click refresh without any errors. Thats why the Refresh Board option is there. Once you click that, I believe the browser refresh option should work.
"note.. I believe this is how it works,., but because this is java , I could be wrong.. straight browser without java works that way"