At first one may wonder if it is merely a computer know-how problem . . . however, it seems some VERY computer literate folks are unable to resolve this issue on their own machines. Some of the suggested fixes are easy as cake to a computer literate person, but most are unable to have any success with this issue.
I think that is the oddest thing in the world.
One may wish to attempt to find the commonality between all these ATI users other than the fact they have an ATI card. Is there a somewhat popular background program these people are running while either installing or playing? Something has to be the common denominator other than certain ATI cards (because there are those with the same cards: one works, one does not). Is it a common motherboard? Certain hardware? Certain BIOS settings? Would any of these affect Civ IV?
I'm following this problem with extreme interest (or, rather, extreme dismay) because I have an ATI Radeon 8500LE, and I don't want to buy the game unless I know I'll be able to play it!
But, I do want the game!