This resolution 1920x1080 is not supported by user patch 1.4RC; you can however switch to 1680x1050 instead.
User Patch 1.4RC desktop resolution 1920x1080 or 1680x1050 is not available
Manually setting the 1920x1080 resolution through registry will cause age2_x1.exe to crash, you can however use 1680x1050. If you have more than one screen, the highest resolution available is 1280x1024, you can however set the desired 1680x1050 resolution in registry. Keep in mind, that you have to repeat those steps below, when changing the game options in game.
Important: This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/322756: How to back up and restore the registry in Windows
Start > regedit > Run as administrator
Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Microsoft Games\Age of Empires II: The Conquerors Expansion\1.0
Set the correct values for the keys below, make sure to click the dot in Decimal first:
Click on Decimal first, before entering the desired value!
- Screen Size: 1680
- Screen Height: 1050
- Screen Width: 1680