man looks like there hdr lighting, weird.
a few things to try
step1. delete the folder called skybox from cstrike/material, test report bak
with good news.
step2. umm try downloading re textured skybox's from http://www.fpsbanana.com/texturecats/7 . who knows mite fix be able to cover the problem up
step3. ask some1 else
step4. if all else fails. buy a new g card