Have you found a solution yet?
In my case, I also experienced crashing, mostly when I engage in a dialogue with an NPC, and sometimes as you described, within a few minutes of gameplay.
I was not able to find someone on various forums that could replicate or have the same problems I did but I found an article written by gameranx when I googled my crashing problems.
I am on my second play through now, still good.
One of the solutions, which I applied to me and it worked. was to set the FPS limiter to 60 fps and Vsync on and shadow details low. It mostly stopped the crashes for me.
On very rare, random times, it would still crash but I could go a few hours without crashing. It would still crash while I dialogue but it is rare.
It could be that my system is relatively old so I don't know if it contributed to my crashing problems.
Xeon 1240 E3 @ default speed, 3.6ghz
1070 TI, undervolted
8 gb ddr 3 memory @ 800mhz.
The game is installed on an old Intel 80gb X-25 SSD.
Playing on 1920x1080 @ mostly high settings. I get 60fps, sometimes dips a little below on specific areas.
Good luck