Describe Current Behavior:
Enemy targets killed by poisoned weapons die and spring back to life, almost like zombies, and do not die for good until the damage-over-time period of the poisoned weapon expires.
Describe Expected Behavior:
Enemy targets killed by poisoned weapons should stay dead and not spring back to life.
I've always encountered a bug when using poisoned weapons that do damage over time (e.g., poisoned arrows, bolts, etc.). For example, when the enemy target is at a low hit point level and I hit him with a poisoned arrow, he will not die normally when all his hit points are depleted.
If I recall correctly, once the target's hit points are depleted, he collapses, usually drops all his droppable weapons and items, and springs back to life. He will not be able to move from the spot where he died, but my party members will continue to attack him in his "zombie" state and he will also attack in melee if any of my party members are close enough to where he "died." He eventually dies for good, presumably when the damage-over-time period has expired.
I used to love using poisoned weapons in games like Icewind Dale because it was great for disrupting spell casters. But I stopped using them in BG and BG2 not only b/c it disrupted my battles (party members kept attacking him when live enemies were still around) but b/c it seemed so strange to me.