Leader of the Crouch Jump Kingdom
Otherwise know as The Moose, "Italiano", Fallen, and Lodanumbrz
Posted by: R0UGE ASSASSIN
Halo P.C forums??
This is the Halo PC forums...
Either way, only thing I can recommend is completely removing all information about Halo 3 from your system. Complete uninstall, remove any saves, cookies, anything. Once that is done, reinstall, and you should have a chance to use the CD key again.
If that doesnt work, you may need to contact customer support of some kind, I believe there is a contact for Halo CE: Mac.
Hope you get it working,
Cheers