- last post: 01.01.0001 12:00 AM PDT
Some games won't work if you have a demo version installed, or vice versa. I had the Flatout demo and bought the retail version (game's crap JSUK) and it wouldn't work until I uninstalled the demo. I also downloaded the demo for Empire at War and when I tried to run it while I had the full version installed (Was having problems with the copy-protection program) the demo wouldn't run until I uninstalled the full version.
I would expect most people would be able to run both programs with no problems, but every computer is different and what might work for someone else might not work for you. So just try deleting the full version of Halo and trying the demo, or tell your friend to go buy the full game.