Fencer: Two lines can disappear after a move in a corner which completes two perpendicular rows, so I had thought the same applied to parallel rows. The way it is now, sides of the board can become "blocked" and the game's dynamic aspect is reduced. Still, BrainKing is the only site to have this game, so there is no precedent to contradict your method, and maybe I'm just annoyed at losing. :)

Still, have you ever played Tetris?