Multi textures on one object and other

[Klarden]

Hi, I'm using ATI Radeon HD2600XT 512 Mb (latest drivers 7.12), Athlon x2 5600+ (2,6 Ghz), 2 Gb dddr2 RAM on XP and experience strange glitches (look at the attachments). I'm pretty sure it's ATI fault, but i may be wrong. So, the first picture is how most of the objects in game are drawn. Second picture is how the situation changes when the light source is near. Third picture shows that everything becomes (almost) as it should be when checking any object. And the last picture shows this brown-grey-ish textures that may sometimes appear. This "sometimes" turned into "everything is brown" after i tried to load an old savegame i made on my previous PC config. I'm just wondering, maybe it has something to do with the option of "geometry instancing" being always turned on on the latest ATI GPUs. And yes, i have tried all rendering options, different videocard options (including turning everything off, catalyst a.i. as well, and setting everything to max), reinstalled the game and tried playing it on 7.11 catalyst version.
P.S. I didn't try to play on the retail version, though, only after applying the 1.02 patch and 1.03 beta...
P.P.S. Oh, and with all this fun i forgot to mention flickering which appears in the places where textures are otherwise normal, like the small spider caves where you need to find the ladder to go back up.