I suggest you totally remove the demo and ANY mod files you might have downloaded. Then, download a registry tool from
www.downloads.com) - regedit is a good one. Then get that to remove any Empire at War files left in your registry.
Once you have done that, reboot and then re-install.
DMUK
I really appreciate all of the help, unfortunately nothing seems to work and as such I will just try to return the game. Thanks