All right, I ran into a peculiar problem with Cossacks: When I enter the game and set resolution, I can't do so again, resolution selection disappears and when I confirm any changes, game starts crashing with unspecified resolution. And I don't really care for the most part, except I find the game speed too high and the only way to change it is ... you guessed it ... on the same options screen as resolution. So, is there a config file or registry entry anywhere I could access to either set the speed or reset resolution after the game breaks it? Or is there a hotkey to change the game's speed? (I've tried D that I found somewhere, but it doesn't help.)

I solved the issue by running the game in Windows 7 compatibility mode.
Of course, I can't mark my post as a solution, so if somebody could write something and qoute this post, it would be much appreciated (so it appears on the support page)

Thank you for the quote. It seems GOG got Stack's responce time down now :-P