I was fighting the ball in the underdark that has six different creatures come out of it when you mess with the gems and have lost Minsc. I was fighting a guy that was crazy and couldn't talk. He cast imprisonment on Minsc and then minsc disappeared from my party. I killed the guy, but the game thinks that the guy is still alive because it is casting spells at me from thin air. Each time i walk up to the landing something targets me and shoots spells. I have the equipment that i picked up when the guy died too. Now I am wondering how do I get Minsc back or can I get him back at all? Minsc stuff is gone also. All my party members still see the guy casting, but there is nothing to target with weapons or spells. The party simply goes to that place then just stands there to get hit with spells. Weird?!
WolfgarJr

Yes i had Viconia disapear mysteriously without Dying too-- i cast a "freedom" scroll in the area and she was back. Yes she left the group and everything, and i had to reinvite her there on the spot. (In a dungeon off the underdark..fyi) There's a mage too you have to do the same for- (a quest) if you talk to the Duergars in the south of underdark they will tell you.