Something that so far has worked for me on CTD. It didn't solve all of them but it did cut the number down alot. There were some places that everytime I went there I had a very high chance of CTD. I tried a lot of ideas, but one that eventually seemed to have worked is changing the texture quality. I know it doesn't seem like it would work,
but I crashed more often on the lower settings than the lower medium settings. I finally settled on the medium low setting and those areas where I was crashing all the time I can go to without crashing.
I moved the setting to one of the low settings, don't remember which one now, and I crashed almost immediately. It seems like the texture quality causes crashes in some areas while trying to render a mesh. Anyway, tossing out this a another idea.