Forest terrain is pink

I've just installed Civ IV (via Steam) on a new desktop running Windows 8.1 and I'm having a problem with the graphics. Some of the terrain is pink (see screenshot). No mods installed, just vanilla Civ IV.

I'm pretty sure my graphics drivers are up to date. I've verified the integrity of the Steam download. The Build Version is 1.7.4.0. I've tried running the game with compatibility set to XP SP3, but the problem persists.

Pink things in Civ4 usually mean that you are missing some art files or texture files. I would reinstall and see if that solves the problem.