I get an "Access violation at adress 00443878 in module 'AoWSetup.exe'. Read of adress 00000000." message when I try to change the graphics in the "settings" option of the AoW.Setup.exe file. How do I fix this?

Also, is there any HD-mod for this game?

I have same problem, and asked for Support to help me, but so far they can't help me out. My case, it seems some sound driver cause trouble. I am checking the cause of trouble.

In this thread there are possible solutions to this error message, hopefully one of them will help you: https://www.gog.com/forum/age_of_wonders_series/game_not_displaying_setting_errors