It seems there is a significant problem with Summoning Dolls causing you to CTD when using them. Some of the problems have already been reported on the Technical Issues page.
You may want to avoid them at all for while, or definately save your game before summoning one. They seem really useless in the game except as mules anyway, and since the weight issue has been resolved, not using them is no big deal.
Just keep it in mind, it is not a gamestopper at all.
