I got Stalker from a free-cd in a gaming magazine years ago.
If I recall correctly, it was 1.004 version on it, I only discovered it had another patch (and an installer for a bonus monster that requires a passsword) years later.
Granted, I was 16 at the time, and didn't know how to computer very well.
I only remember one crash at all and that took me spamming like 20 grenades while fighting 15 soldiers or some shit. I actually though it was perfectly reasonable to crash like that.
As for bugs, same as >>16818254, one quest marker didn't disappear (it's actually not 100% bug, it's a stupid feature about fetching a gun that some bandit is carrying, the marker doesn't update to his position because when you get close for him to go "online" with the A-Life system, he suddendly moves to the bandit base leaving the quest marker behind, killing the bandit solves the problem).
First time someone linked me a mod, the only diference I could tell was "Uh, I can run faster? and carry more shit? This is getting boring pretty quick". Go figure: the retard linked me Complete 2009, and it took me a couple weeks until I saw a thread on /v/ with actual proper mods.
If you want to see proper bugs and weird shit, get Stalker Soup. THAT was a wild ride, and when I look back at my time in it, I think it's exactly like how people describe vannillla.
Except that mod was made by some half-starved, high-on-krokodile mad ruskie, not the actual vanilla game.