When I try to reset the resolution the game blacks out for a minute then rerenders, I get an error message saying the game can't find directx (double checked that I had it installed) then the game won't respond to any mouse clicks. I can still move the cursor and still have the majesty cursor and can *sometimes* get it to make a noise when I click but nothing happens and i have to hard close the game from task manager. What do?

Bumping this old thread to satiate anybody else who was lurking (like me):

1. Reinstall Majesty Gold HD, then start it up
2. Before touching anything else, click on ADJUST SETTINGS and then click SCREEN RESOLUTION
3. Click the box next to Use DirectX 9 so that it is unchecked, then click APPLY
4. Exit, then restart Majesty Gold HD
5. Leave that unchecked box alone (otherwise, repeat steps 1–4)

That should do it. I can switch between resolutions without any problem now. Here’s a screenshot just for reference on how it should look.

I have the same issue, I've tried to follow these instructions, but I'm still unable to solve it.
When I uncheck the DX option and click "Apply", the game shows an error message which says that DX9 are not installed (but they are, I installed the June 2010 version as required). Closing the popup message makes the game not respond precisely as described in the opening post.
I have to force close the game.
As I restart the game, the DX9 option is still checked.

Is there anything else to try? I read about a DX Wrapper, but I'm unsure how it works.
Any help?

EDIT ------------------
I've just found a way to solve it.
The above instructions actually work, the problem is that you must close the game using its "Exit game" button, but you can't see it if the main menu is covered by the options menu as happens in this case.
Once you close the error message, press "Esc" on the keyboard and then "Y" which is the way to close the game through the keyboard. Restart the game and the DX option will be unchecked, then you can change the resolution.