GOG Support advised:
1) Please make sure that you use "Run as Administrator" to install and to start the game (right-click on the shortcut or setup file and select "Run as Administrator"). If you are running the game via Galaxy, you can skip this step.
2) Please reinstall the game AND add it to your anti-virus/firewall software's exception/trusted list. Simply disabling firewall or AV software could not be enough, since some of these software are running still in background or in services list. If you are using Galaxy, then please add Galaxy as well.
3) Please make sure that DEP (Data Execution Prevention) is using its default setting. To do this, follow these steps:
I) Open Menu Start
II) Right click 'Computer' and click 'Properties'
III) Click 'Advanced system settings'
IV) Open tab 'Advanced' and click 'Settings' in 'Performance' section
V) Open tab 'Data Execution Prevention'
VI) Change DEP setting to the first option (Turn on DEP for essential Windows programs and services only)
VII) Confirm with OK.
4) Please make sure that you have set proper permissions to read and write in the game installation folder. To do this follow this guide:
http://winaero.com/blog/how-to-take-ownership-and-get-full-access-to-files-and-folders-in-windows-10/
I did all this... the problem is still there as before, same symptoms.