Czuch Czuckers: That I don't know. Maybe it has something to do with how your next game is calculated (should it be of the same type and you have no more games of that type, for instance?) or on your default option when submiting a move (if your default is "go to the main page" rather than "goto next game", for instance).
But I'm just guessing now, of course. Better wait for an answer from Fencer if you can't figure it out...