I have had one report of a possible workaround, I would be very grateful if a 'crasher' would try it:

Uninstall the game completely. Then reinstall and before you ever start a new game, enter your reg code. Then exit the app and reenter it and start a game normally, etc.

Please let me know if this works, anyone. The theory is that the process of registering is corrupting an existing game-in-progress, and registering before a new game was ever started might circumvent that.