Before doing that you might want to try this:
The below is a gazillionth repost of a walkthrough - if you do not have Warlords ignore that part. It is written for XP so if you have Vista the paths might be different.
install the most recent version of DirectX 9c from
Microsoft
then do the following for a clean reinstall:
Uninstall and Reinstall Civ4 Warlords BtS :
Try to follow this order when doing stuff:
Use Control panel to uninstall Beyond the Sword, then Warlords, then Vanilla
Delete "...\documents and settings\<username>\my documents\my games\sid meier's civilization 4" manually
Delete "...\documents and settings\<username>\my documents\my games\warlords" manually
Delete "...\documents and settings\<username>\my documents\my games\beyond the sword" manually
Delete "...\documents and settings\<username>\application data\my games\sid meier's civilization 4" manually
Delete "...\documents and settings\<username>\application data\my games\warlords" manually
Delete "...\documents and settings\<username>\application data\my games\beyond the sword" manually
(note: application data is a hidden directory so you need to configure windows explorer to show hidden files, also these directories in application data are sometimes removed by the uninstall routine)
Delete "...\Program Files\InstallShield Installation Information\{CFBCE791-2D53-4FCE-B3FB-D6E01F4112E8}" (Civ4)
Delete "...\Program Files\InstallShield Installation Information\{3E4B349F-10B5-4586-9D99-489A90A8B228}" (Warlords)
Delete "...\Program Files\InstallShield Installation Information\{32E4F0D2-C135-475E-A841-1D59A0D22989}" (BtS) (note: InstallShield Installation Information is a hidden directory so you need to configure windows explorer to show hidden files).
Install Vanilla, immediately patch it to 1.61 (download it fresh from
here)
Install Warlords, immediately patch it to 2.08 (download it fresh from
here)
Install Beyond the Sword, immediately patch to 3.13 (download it fresh from
here).