Texture Bug: Pink!

[Red Falcon]

I am experiencing an odd bug where certain textures, usually the outside walls or roofs of buildings, appear as a bright pink and black checkerboard. The game is playable, but it is...wierd and quite distracting. Any help would be appreciated. I am running a 2.0 Ghz Pentium IV with 768 mb RAM and an ATI Radeon 9600XT.

 

[doomed - uk]

Well, the official advice here mentions "purple and black checkerboards" but I've no idea if what they say to do is helpful.