I have gathered all the Aetherium shards for the Lost of the Ages quest and am supposed to go to the Ruins of Bthalft. I have been there before, so I thought to use fast travel, but I just got a CTD. I tried walking there from Ivarstead or Treva's Watch, but whenever I come within say one ingame mile from the ruins, also a CTD. This never happens anywhere else in Skyrim, and I have really travelled all around the place! Anyone?