Having some of the same issues. your error looks like C:\Program Files\DCS World OpenBeta\bin\dx11backend.dll. My errors were with the weaponsBlock.dll I deleted the file and then did a repair using the DCS repair tool. I think this helped, however I still need to do some testing.
I am flying in SP with an AI wing man and that is when I have the crashs.
I ran the same mission with out the AI wing man and did not have the crash but this was also after deleting and repair of the weaponsBlock.dll.
good luck.