So, I've been having this issue for a while, and I'm finally going to fix it: http://cloud-2.steampowered.com/ugc/918991495528245160/F22A46544F3C04F1A574E85A6B1E392F002295ED/
I've determined that the issue is the HD texture pack DLC. It must have been corrupted or something. The issue is, I can't for the life of me get Steam to download it again. I moved the bsa's and esp's for it out of the data folder, and I've validated, I've restarted Steam, I've gone to the DLC page and clicked play now.
No matter what Steam refuses to acknowledge that the files are gone and it that it needs to reinstall them.
Does anyone know how to make it do so?