Bugs happen related to quests. Let's say I just finished a quest once/ or started a quest and if I try to load saves the bugs happed. I think you are saving quest variables globally or something. You need to fix that
we are aware of this problem. Sadly we do not own the rights to the quest plugin we are using In the game. The good part is that it can be easily avoided if you just open the quest tab on your menu after loading a game. That should prevent or from ever crashing again.