Since user above initially use GOG Galaxy im answer only for this online galaxy build. But this rare time, current offline build is better - it have more content. So, as one of the solution to try - if validating do not help, try to download and install offline build.
(polish Galaxy version is correct), english one miss 12 blnk heroes and probably something more from maps folders)
-------------------
Offtop here: (GOG version still based on unpatched 2005 Gold release - it is really miss a lot of heroes\maps from both Disciples 2 game, along with 3.01 patch for RotE game)
(GR 2005 Gold - from CD edition is partially updated to 2.02 - but only remain file from 2.01 is main menu dbf file where only this one string with number are outdated - you can just change it in any Office\dbf editors from 2.01 to 2.02
RotE is completely 3.0 on 2005 Gold CD and only exe files are 3.01 - same for GOG, 3.01 patch files is completely missed here, along with DLC content from 2006 Gold edition
and RotE Gold Upgrade 2006 DLC installer from one of the near threads
is not patch even if main menu number changed, patch should be installed after Gold Upgrade DLC for RotE)
/
offtop end ----------------------------
jd44: Did all that, no change. Win 10
GOG put unneeded (especially with build-in GOG wrapper (sic!)) compatibilities. Uncheck everything from all exe properties. Keep only admin run and only on galaxy exe if you do use only Galaxy to start games (or set game exe admin run as well).
Because, again. NT 6.1.7601 is Win7 Sp1 *core* version (full version number for Win7 x64 Sp1 with partially 2014 updates is 6.1.7601.24384). 6.2\6.3. with some additional numbers is Win 8\8.1 core. I never use Win10, but as i google it now - it looks im right. Win10 core labelled as WinNT10 as google say.
So it is something wrong with Windows entirely. Or it is Win8 very outdated. Or it is Win10, but again - very outdated updates build. Or most likely some compatibility enabled... If this is crash report from created log file in game folder - it is compatibility enabled.
If this is crash report from Windows\user AppData crushdumps... this is strange...
Try to turn it off. If this not help - experiment with that.
Currently GOG always put fullscreen optimisation even if you use Win7 and there is no such option\very differ. This is not needed with they own GOG wrapper. And mostly not needed at all even on Win10.
If you cant solve this, any settings in DXCFG not solve this - rename _ddraw.dll file. Make sure game work.
And later - use another wrappers. ddraw.dll file from narzoul, degevoodoo or DisciplesGL GLwrapper from Verok - there is link above in this and some other threads on his blogspot site.
DisciplesGL require some settings edit ofc. Nothing matter what you use - settings first. Set 800x600 in the game configurator and custom resolution in DisciplesGl itself (use F4 to toggle borderless windowed\windowed to access to wrapper settings menu).
GL wrapper from Verok is more than just compatibility wrapper - this is mod.