SOLVED!
I had the same issue on my Laptop. The only thing my both systems have in common ist the Anti-Virus Software (Bitdefender 2018). You can read more about the solution here: ntdll.dl Crash [Solved (BitDefender Antivirus)]
After I added the game to the whitelist of Bitdefender, I was able to test-play more than 45 minutes without a crash on my Laptop. I'll test it on my gaming system soon.
At First I had problems to start the game on my Windows 7 Laptop. It crashed immediately after I started it. Under another topic I read about that issue. I loaded an older Version in Steam (that one for older save-files) and that one works. After that I loaded the newest version ( 2.21) again. The game started without a crash. Maybe that experience could help you for debugging.
I'll report if I experience more crashes.
Thank you for your response an your help. I'm locking forward to play your game in the full release version!