Installing Halo PC and CE

I keep getting the same error (Setup needs to modify the file _, which is currently in use by another application.) when attempting to install Halo and compatibility mode made no difference. I installed an old program with compatibility mode perfectly, while it did not work without it, so I've no idea where to start looking...

Win 7 home premium
64-bit

Well, Microsoft deems it to be officially incompatible, so even if you do get it to run, it may not do so happily. Some people have gotten it to work, supposedly...

What's the name of the file it mentions when the installer fails?

Sorry, should've check before posting, but it was just silly McAfee... :-/

And it runs just fine, despite the whole "officially incompatible" statement.

Thanks for trying to help.