I'm playing on a Mac, on Steam.
I'm at the beginning of chapter 2, when Katjaa is talking to me before she's grabbed from behind by the zombie. I barely have time to select a reply and the game freezes. The zombie sounds go on though and there's nothing I can do. I tried rewinding several times but the game freezes always around the same point (sometimes a little after). So I am stuck, unable to do anything but listen to zombie sounds go on and on and on.