Guards attacking on sight in Nashkel

I have a problem: the guards in Nashkel attack me on sight, even though my Reputation is 13, and it says that I am Popular (my character is a Chaotic Evil Half-Orc).

I think it might have something to do with something that happened at the start of the game, when I tried to force open a lock, and someone saw me; I killed the guard, and now I'm hanging around wearing his armor and stuff, but I have been a good boy since then.
Is this some kind of bug? Should I restart the game?

EDIT: I donated 1.5k gold to the temple next to the Friendly Arm Inn, my reputation increased to 14, I went back to Nashkel, and I'm still being attacked by the guards. Is this because I'm playing a Chaotic Evil character?