That's pretty typical for PC games, particularly RPGs. You should read the patch notes for games like Fallout 2 (villagers will no longer turn hostile for no reason) and various Bethesda games (party members will no longer fall through the ground and end up in a distant village). This is nowhere near as bad as that, it mainly seems to be stability and optimisation problems. Actually coding errors in terms of how quests proceed is actaully incredibly polished for a PC RPG at launch.
