My game crashes ONLY when the graphics is put to 1920x1080. Everything up to 1600x1050 is fine (I checked) and all FX options can be on or off, no difference...

Is there an easy way to fix this, or am i stuck with this?

yeah had the same thing and tried contacting gog support. i guess this game does not like 1080.

I found the solution for playing at higher resolution, in my case 2560x1440.

Download files from here - https://github.com/UCyborg/LegacyD3DResolutionHack/releases
and extract them to you Crusaders of Might and Magic directory.