To describe the mission, you get pulled into the black book and it is very dark, there is some type of health drain effect which is turned on and off throughout the area. When the effect is turned on it makes a loud sound.
When I got to the end of the quest and tele-ported out using the black book that sound was still in effect. I tried to leave the area and f.t. but that did not get rid of it. I reloaded a save so that the sound was no longer present.
If it helps to determine which book it was the options at the end were +10% combat efficiency, -10% spell cost and one other.
Any help is appreciated.