Had something similar, I couldn't end my turn and game would get stuck after surrender.

I changed the Video setting to "windowed", instead of "fullscreen". It seems this fixed all my problems with the game constantly getting stuck/freezing and/or turns not ending.

Thanks a lot. It worked.

I have same issues...
I realy like the game, but atm it is hardly playable.
I am stuck at the cow puzzle too :/

This didn't work for me. It still ended up freezing after I passed my turn. It's funny, it only happens when I'm going to win on the next turn, like the game knows it and doesn't want it to happen...