Sometimes, a title which was eliminated still remains in the save file, but is held by a character with type = 33 and id = 33. Such a save file will load normally, but will crash when you try to save (or autosave) it again. In my case, the title TEUT, eliminated in 1094, remained in the titles section of the save game. When I tried to save that game, it wrote everything prior to that buggy title entry before crashing. Manually deleting the buggy entry from the save file will fix the problem. But this is something that should be looked at, I bet something like this is causing the crash-on-saving that people are reporting.