On Age of Empires III, a computer level in multiplayer is stuck at zero and how do you fix this? Please verify what version of that game you are running by clicking on a "Help and Tools" button from main game menu and then an "About" button. That game version will be listed at top of that screen.
You can then download and install patch 1.14 from this age of empires 3 game updates page. If that patch doesn't resolve this issue you can try to run that game in Windows compatability mode. Not all programs are supported and run correctly on Windows 7.
Running it in Vista compatability mode might fix your problem. You can check out how to run programs in compatability mode on Windows 7. You will need to find what that age of empires 3 .exe executable file is, to configure it to run in a different mode.
I would try running it in Windows Vista (Service Pack 2) to test and work your way back to see if it fixes your problem.