I've got the same problem - and only in the Mzulft, Stoney Creek Cave, and Eastmarch Imperial Camp area. Everywhere else the game seems fine. I completed the stormcloaks quest much earlier in the game (+/- 30 hours) & had no problem in this area at that time (I'm on +/- 140 hours now.) Haven't tried the windowed mode fix yet. Previously I was getting a similar CTD anywhere E of Riften, but the fix of deleting all saves, then going to an indoor location & resting >7 days seemed to fix that problem, but isn't helping this one. The problem started when i was using my old graphics card & continued with the new one, so I doubt its a hardware issue; and it continues with both the latest stable patch and the 1.5 beta patch. Please post any fix or possible fix you find