Hard to say whats going on for sure without knowing your specs.
What you absolutely need to do though is monitor your gpu/cpu heat and make sure your fans are running 70%. This games engine and poor optimization = massive heat. Computers now days are designed to crash/reboot when too much heat is happening. and to give you a baseline for temps my rx 480 fans 70% = 55 celsius , cpu water cooled 45 ish under load. If you see temps in the 70s or higher that could be trouble.. Newer hardware will start to downclock mhz when temps go too high resulting in very poor performance and crashes..
After you determined heat isn't the issue.. I would back up first then delete the following files:
System.CFG (in wolcen main folder)
game.cfg (in wolcen/wolcen folder)
shaders entire folder 6mb ish (in wolcen/wolcen)
wolcen.exe in winx64 folder
game.cfg in wolcen/game folder
Optional Engine folder delete..
So essentially what you are forcing is the game to redownload some important config files that are stock, your blowing out the shaders folder for stock ones, new exe because I don't know if you've changed compatibility mode stuff in it and the game should run fine once you load it up if it downloads those files again. You might have to relaunch steam a few times to get it to trigger the downloads for those files you deleted but I did it last night and had no problems.. Maybe scan/repair etc...
Deleting those files above essentially saves you from uninstalling the game and redownloading.. Since those are the major files that can be corrupted and causing your issues and there small enough to redownload and save time by just knowing which ones to delete without having to do a full redownload of the game.
The other thing I will say is. I think this game engine is a fickle sob.. It likes 60hz monitors and v sync on to cap frame rates.. Why? I don't know for sure but no vsync will generate way too much heat and cause crashes or graphically anomalies.. and possibly burn out some hardware if your fans aren't doing their job.. I think 90% of peoples problem with this game is heat or crap hardware that isn't good enough to run the game. Cry engine is probably the most taxing engine known to mankind.. I would never use it for a game if I had a choice because you limit your playerbase to only those with the best hardware.
Take a game like torchlight 2 or diablo 3.. Both those games run perfect on most systems.. And they look just fine.. Why they chose to use this horrible game engine is beyond me..It just creates a so many problems for people that have lesser understanding of how computers work because you almost need to tweak the crap out of things to get them running smoothly and even then with this engine, there is always still issues.