This references the chess game which comes with a MacBook. Mine has never worked reliably. At a certain point, it will reject a perfectly legal move, and pass the move to the other side. It will do this whether in Human/Computer mode or Human/Human mode. Then it treats the board it has elected to display as if it were legitimate. Telling it to take back a move doesn't fix the problem. It simply ignores the move it rejected, as though it never happened, but continues to insist that the other color has the move. This is NOT a case of a move being illegal because it's prohibited by the rules, like failing to move out of check, moving into check, or trying to move a black bishop onto a white square. It's version 2.4.2. Naturally, this makes the application worse than useless. Anybody have any thoughts on this?