I have a similar problem.
SPOILERS AHEAD
I do the final battle, I watch the entire conversation with Lucian, and then it freezes. Alt+tabbing back to windows then causes the game to close down.
I've already seen the final movie that is supposed to follow (I checked the Divinity 2 Video/Story folder), but in game it refuses to load the movie.
Is this related to me using a language hacked version? I do not use a No CD crack and I do have the disk in the tray.