II was having a Crash to Desktop problem in the first part of the Ustengrav Nordic ruin. I'm posting it here, because I'm not sure where to post problems and workarounds like this. May be slightly spoilerish. Upon entering the second large room, or the first one after all the mages, I was crashing on what appeared to be an AI event.The CTD would happen as soon as the entombed Draugr just past the bridge tomb door hits the floor. I tried turning off various mods that I am running to no effect, the CTD always happened at the same point. So I turned on my mods then used the console command of TAI, Toggle AI, to turn off AI for some NPCs. This seemed to work, no CTD. I killed all the Draugr, including the one in the tomb, then turned back on the AI with the TAI console command. No Crashes. I had Lydia as my only follower. The Draugr in question ID was 0005204f I have a rather lengthy mod list so won't post it here, though at first I suspected ASIS, Automatic Variants, Skyrim Performance Mod and WATER. Though on research, it seems that Ustemgrav is one of the bugged areas and has never really been fixed. This is an FYI post, maybe someone better suited than me can track down this bug.