Try this...
The same thing happened to me after installing ToB and the latest ToB patch.
You start out in the elf celebration area, then part of your party goes to the dark area with the faces carved of stone. Use one of those party members to click on a face and follow through the dialogue.
After this, the screen switches back to the elf celebartion room with the other half of your party. There you will encounter another child of Bhaal (walk around the room if it doesn't start automatically). Defeat her with whoever you have in her area, and it goes to a cut sceen.
Afterwards, your party is back together and ready to move on.
I found that by reloading my final save from SoA I could get different combinations of the party split. You want a split where your main character and some "heavy hitters" stay in the elf area.
Those that go to the stone face area really have nothing to worry about, but the other Child of Bhaal in the elf area is out to kill
[ 11-04-2001: Message edited by: Ronn_Bman ]