I'm having a recurring problem in the big bad sudoku book, where it freezes up during the game. I have to exit entirely, and then reenter. Sometimes it brings me back to where I am, and sometimes to my last complete game.

It's not something that is happening wide spread. It could be simply that you need to delete and reinstall the app.

Also would be helpful to know which device you have, what iOS version you are running, and to make sure you're on the latest version of the game.

Let me know.