This has happened 3 times now. It's right after Heimlock or w/e summons Lambach and we're running through the forest after talking to Lambach and the first heart of corruption appears. As soon as I start to fight it my game freezes and I can't do anything. I have to use task manager to close the game. I'd really like to continue the story but apparently this is as far as the game wants me to go at the moment.