Godfrey, it was probably the backspace you hit - usually it's fine, but sometimes it causes "back" on browser. I think it depends if focus is in a text field (text field consumes the keypress) or elsewhere (the keypress falls through to the page navigation as a whole). We have discussed this problem here:
http://www.sudoku-champions.ca/forum/index.php?topic=6.0 and the solution is to play in a new window. This is why Peter gives us this option, I think it was directly as a result of the discussion. You see, if you choose a new window, there is no "previous" to go back to, and therefore the backspace simply does nothing.
