So I go on voobly, I host a game and launch. I choose game settings, I ready up and start the game...then it freezes and an error message says “Age of Empires Expansion has stopped working”. What is the problem?

Hello,

There can be many reasons for your game to crash. We will need to figure out what is triggering the crash.

Start by hosting a game in single player mode from within Voobly and see if its working fine.
https://support.voobly.com/display/vkb/GGG+KB1032+How+to+start+Single+Player+Mode+through+Voobly

If everything is working fine in single player mode, set the in game resolution to the lowest possible (800x600) and then exit the game. Now start a normal game from Voobly and change the resolution to your native desktop resolution.

But before you do that, please ensure that your game room settings are exactly like this:
[You must login to view link]
You can verify this by hosting a game room in any lobby

If the game is crashing in single player mode as well, you may need to reinstall your game. In that case follow the steps mentioned here to perform a clean installation of the game:
http://support.voobly.com/display/vkb/KB1019+Clean+installation+of+Age+of+Empires+II+with+the+latest+patches

If you are using the HD version from Steam, follow the steps mentioned here to perform a clean installation of the game:
http://support.voobly.com/display/vkb/KB1054+Clean+installation+of+Aoe2HD+with+compatibility+patch