This is from
http://planetcivilization.gamespy.com/
Official Update from 2K Games on Civ4 Bug fix.
13:22 PST | NooM | Print News | Mail News
Since many people were having so many problems with Civilization IV, apparently incompability issues with some nVidia drivers as well as ATi cards and AMD processors; I contacted 2K Games and Firaxis regarding the issue, and it seems an update of sorts is coming tonight. Here's what Tom Bass of 2KGames officially says:
There will be an update to the CivIV.com website tonight that will offer
solutions to the most common errors that users have been experiencing.
2K Games and Firaxis have been working diligently to determine
workarounds for these issues, and working with our hardware partners to
determine the solutions. We have been monitoring Civ forums and have
been speaking with consumers, and thank everyone for the support and
information that has been provided.
I do want to clarify that the issues that have been reported are not
affecting all or even the majority of ATi cards or nVidia drivers. It is
our intention though that the game works on systems that fall within the
minimum system requirements, and thank users that are experiencing
issues for their patience.