I know my "rig" is of borderline minimum recommended setup, but I have the very same problem - tried many tweaks that were suggested elsewhere - including reverting back to older catalyst drivers, changing several variables in the My Games/Far Cry 2/gamerprofile.xml (refreshrate, vsync, maximized, drd9 instead of 10, etc.), tried setting everything to "Application controlled" in CCC, disabled overclocking, and maybe something else I don't remember- all to no avail.

It would appear that this is a memory error (I also got the IRQL_NOT_LESS_THAN_OR_EQUAL BSOD although other times my pc just rebooted) but all users reporting it have Radeons. Maybe it's a combination of an ATI gpu + an ASUS motherboard (I also have one). AND Kingston RAM, maybe?

Well, I hope we solve this one soon. I was going to buy a new GPU this week anyway, seems I'll have to pick up a new set of RAM as well.

System specs: ASUS P5RD1-V, 2x512MB of Kingston RAM, ATI Radeon x1950.

This is a VERY nice topic, because the game itself, for one, deserves a LOT of praise, like some people already said, and the 1.005 patch deserves even more of it and so do some of the really nice mods.

I use the following (in order of installation; no bugs have occurred ever since):

1. STALKER Ultra_graphic_mode_v1.1_fixed.zip (from GameSpot)

2. S.W.O.v2.0_FULL (Weather Overhauled - comes with a sharper texture pack as well, really worth checking out, because I've noticed NO performance drops with it, just longer level load times)

3. STALKER aliVe 1.6 for 1.0005 (changes AI, adds tougher wildlife and also modifies weather cycles&related graphics somewhat)

Now, the thing is, when stalker came out a year ago, I had this rig: Pentium D 2.6, 1GB RAM and Radeon X1600 Pro (an outdated gpu even then, just like the whole system). And that original game on that rig even with the 1.003 patch really sucked balls for me, because even on static lighting and all the settings at lower than mid, the game more than often crashed, XP restarted, I even had suspicions of gpu overheating or RAM problems.

Now today, I'm playing the 1.005 patch and the aforementioned mods on 1024x768, MOST settings on max (excluding FSAA), WITH dynamic lighting, I kid you not - ON THE VERY SAME SYSTEM (only modifications are newer ATI gpu driver - no OC has been done). While I do suffer really long level load times, the fps drops below 15 only a couple of times in action right after loading the game, rarely afterwards. So this is my experience with Stalker - and I must say that if my Ukrainian neighbours are given the resources they need (beta-testing and optimizations-wise) for Clear Sky, they'll do one heck of a job on it. Think Crytek job on Crysis after Far Cry ;)

And I'll allow myself to express my opinion on AI as well and even compare it to Crysis:

Stalker's AI was just good-nothing too fancy, but generally well done, while Crysis was prolly the dumbest one I'd seen in a recent FPS. I played the whole game on delta and the ONLY place I experienced difficulty was when I had to escort Prophet (cause he'd freeze-notice that no AI was involved). I had a laughably easy experience and AI stupidity was sometimes truly horrendous.