I bought ee2 on my laptop and both desktops, it runs fine, but when I try to change the screen size the mouse is off centered, on the desktops that is fine but on the laptop I can't see the whole screen, and if I move the screen the mouse will be off centered, so I can set up a game and everything I just can't click done to start the game.

Also when I try to make a lan the game just says this cd key is already in use.

You're probably a victim of the windowed mode version. Gog decided that the windowed version will "fix" compatibility problems with game. If you want to play the game in the full-screen mode (which incerases performances) - try Unofficial Patch 1.5: https://www.ee2.eu/patch