Trying to save causes the game to freeze

It doesn't happen every save, but every 2-3 saves the game will freeze at the save screen (it will show an empty progress bar, with the tips scrolling underneath). The only recourse is to quit the game, at which time all data not previously saved is lost. Because it happens so often it makes the game basically unplayable. I've also had it happen when trying to exit the world as well. Started with the update just before christmas (never really happened before that).
Only thing that might help is that we always play two player split screen when we're playing. Thanks.