did you try lowering the graphics settings can you actually go into the options screen? and vanilla and warlords where patched before installing BtS? I am asking this because I have seen reports on corrupted patch installs when BtS tried to patch those itself?
I fear uninstalling and reinstalling may be in order, here is a guide:
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}"
Delete "...\Program Files\InstallShield Installation Information\{3E4B349F-10B5-4586-9D99-489A90A8B228}"
Delete "...\Program Files\InstallShield Installation Information\{32E4F0D2-C135-475E-A841-1D59A0D22989}" (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.