Very interesting topic. Thanks bcsp! Sadly, I'm having the same problem right now. After becoming a thane of all of the city, I began Dawnguard quest. Immediately after the rescue the Serana, this problem has occurred >_< I'm using DynDOLOD 1.47, FNIS 6.2, several custom-voiced-followers, and a number of immersion mods (Checko's mods, Isoku's mods, Hunterborn, RealShelter, WetAndCold, etc...) Trends of strings in my save is as follows (# is save count):