I seem to have a problem with directx games on my X1900XT 
If I start Counterstrike Source or Test Drive Unlimited I get a constant stutter. On CSS If I ALT+TAB once it doesn't go out of the game and the stutter goes
I was using the Catalyst 7.2 drivers and had the problem. So I upgraded to the catalyst 7.11 drivers, but it is still exactly the same
(also lost 40+fps on stress test?)
The stutter seems to be every second or 2, but it is constant and is really annoying to have to ALT+TAB out just to fix it.
Also on OpenGL games like Quake3 it is ok, no stuttering or anything.

If I start Counterstrike Source or Test Drive Unlimited I get a constant stutter. On CSS If I ALT+TAB once it doesn't go out of the game and the stutter goes

I was using the Catalyst 7.2 drivers and had the problem. So I upgraded to the catalyst 7.11 drivers, but it is still exactly the same
(also lost 40+fps on stress test?)The stutter seems to be every second or 2, but it is constant and is really annoying to have to ALT+TAB out just to fix it.
Also on OpenGL games like Quake3 it is ok, no stuttering or anything.

I just hope it isn't a freak occurence or even intermittent.