I am 30 hours into 1.7 playthrough, no mods. Already updated drivers, verified game files. Everything is bug free except siege defenses. I have crashed every time I've attempted to defend a siege of a town or castle. I've attempted it about 15 times, with 100% crash rate at several locations (Pen Cannoc, Car Banseth, Ormanford Caslte, Talivel Castle, Kranirog Castle).