A quick bump & a status update, hoping that someone might have an answer for this. Problem still persists. I've tried every driver from 9.0 to 9.9 and none of them install properly or work with 5870. 9.10 is the first version that works, but the problem is still there. I'm currently running 10.4 and taking a break from CS until the problem is solved. Nothing so far has worked or even helped, does anyone have any further suggestions? All help highly appreciated.
As sad as it may sound, I don't think the problem is going to get fixed by ATI, hell in CSS ATI still has tons of bugs which they still haven't fixed, even after several years. As silly as it sounds, if you don't have the problem in windows xp, go for a dual boot :x
Heh, the problem is fixed now apparently, running the official 10.4 What did I do, then? Well the only help I can give to those with the same problem is... Watch Pokemon season 2 and change the anti-aliasing filter from box to narrow-tent, 'cause those are the only things I did differently. Which one did the trick? Your guess is as good as mine.
If I have AA set to anything other than Box in Source games they act funny and I get horrible performance. It's always been that way, so I just leave it be...