This looks like a post from a new site trying to generate hits. Their forum hardly has any posts in it. I've ran timedemos with Q4 and I haven't noticed any of these problems with my ATI X800XT 256meg card and the latest ATI drivers.

That's funny :) The Penstar sites been around what, over 5 years now?

Could be ether way. Limited posts on there forums for that type of site. Plus Like I said. I and anyone else I know that have been running timedemos in quake IV have no problems.