Ok, my save game's borked now. Dunno what the shit happened, the game crapped itself and wrecked a save file just by re-loading it somehow. I was in a draugur tomb, helping (involuntarily) two NPCs loot it. First run through I got so annoyed with them I shot and killed them both. Then I found letters on their bodies which gave me a guilty conscience, because I don't actually go around killing NPCs for no reason, only if they are hostile to me.
So I reloaded, and during the final fight the woman NPC disappears somehow; her body was just totally gone, and the male turns on me. I kill him hella easy, but I don't like her dying, or whatever happened. Maybe she fell through the gameworld; I've seen that happen like a dozen times while playing Skyrim.
So I reloaded again, and after that the game became wonky. The NPCs didn't want to proceed to the final quest stage without coaxing (well, me Shouting them through the doorway to wake up the boss, because they were just idly standing there), then they engage the boss and I make sure both survive the fight, and then they run back out through the doorway and continue standing there, not doing anything...and when I press escape to reload yet again the game starts to stutter and the background turns two shades of mustard yellow... (!) This now happens every time I reload.
Worse, the game overwrote the save file with me originally entering the cave with three autosave copies of the exact same save, even down to the same time and date to the minute. So I can't backstep in the saves past the point where it all became screwy now... Wonderful.
Strangely, there's still a save from 18 levels in the past that just keeps sitting there in the save list that I can't remove or otherwise delete, along with a save from the very first cartride in the game. If I were to autosave and then quicksave after loading that one, my entire progress so far would be wiped out. Don't think I can live with that...