Be sure to contact support, too, after trying these things.
From the web, these are some of the best options:
Turn off the game overlay.
Don't execute the program from Galaxy. Instead, find the file in Windows File Explorer and right click it and run as administrator (this, in my opinion, is highly unacceptable this day and age, but many report it working - I suspect they didn't save the game in an appropriate folder)
Update all drivers
Not from the web but what I would do:
After drivers, the game overlay mode, and support options options, make sure gog galaxy is stored in its own folder branching from a drive letter (like D:\GOG\)
Redownload everything
If all that doesn't work, my system is clearly not working well with the game. I'd get my money back and, if I have a relatively high chance of make life changes in the next 2 years (having kids, getting married, dying) and this game is really important to you, I'd wait a few months and try again. If not make changes are expected, I'd wait a year or two and try again. The kinks will be worked out, the community will have built lovely guides for tech support and game help, everything will look better, and you'll likely have more options for story, weapons, characters, and graphics.
