Maybe your Xbox HDD drive is too full? Or is a little bit "heated" ?
I play DKS on Xbox and so far I never met my game/xbox freezes before starting to make a savegame.

Good luck with solving your problem!

Maybe try this: take another xbox game and play that for awhile to see if other games give the same problem ?

On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin,
it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !