Gamma, Contrast & Brightness in STALKER

[DRG.]

Hi there, I have a little problem. Every Catalyst that came after 7.11 won't allow me to adjust the gamma, contrast & brightness settings in STALKER.

The change in visuals is clearly visible when I'm adjusting the sliders, but when I apply the settings they go back to default, even though the sliders remain at the same position.

It is possible to adjust the sliders and not apply the settings (hit esc directly), but everytime I switch a level or go back to the main menu by quitting a game, the issue occurs again.

I tested the 7.11, 7.12, 8.1, 8.3 and 8.4 Catalysts, all of those have the issue except for the 7.11's - the gamma, contrast & brightness settings in STALKER work fine with Catalyst 7.11 (but I won't use those because of various performance issues).

Any workarounds or ideas? I really like to use the 8.3 or 8.4 Cats. Thanks.

Specs:
AMD Dual Core 6000+
2G RAM
ATi HD3870
Windows SP2