I don`t really understand some of the sudden hostile behaviour of some npcs.
For example, i save the two zhents caught by the gnolls in the cave. After that they told me the secret words to enter their hideout. Once there, I delivered their chest and walk around for a while. And suddenly the zhents with te dogs (or wolfs, dont remember) attacked me on sight.
It's not the first time something like this happens to me. I had a similar problem with the goblin camp where the goblins on the entrance where friendly but the goblins inside where hostile.