So after some confusion I think i've found the problem, but I don't have a solution. After reading around it apears Dawnguard became free for a weekend or something, which makes senes becuase i noticed a few months ago people in my game started mentioning the Dawnguard, even though i never purchased the DLC. I recently re-formated my computer becuase i got a new harddrive, and after trying to boot my previous save files Skyrim gave me an error saying that missing data would cause problems and sure enough, my game CTD when I try to load the save. I never asked for this, steam just went ahead and installed Dawnguard on my system without my permission, and now i can't play my save file with 200+ hours of game play. What the hell am i supposed to do?