it's part of an unfinished quest, involving twisted rune, slavers and guarded compound.
kevin dorner has a fix for it. if you scroll down to "Restored Slave Lord & Twisted Rune Fix", you can download it.
however, i recommend using his complete
bug fixes patch. it really is remarkable, all the things he has done to make bg2 the game it should have been, but couldn't be, due to time constraints.
remember, he has worked with the devs and only fixed things that were intended by them.
V***V
