In the quest "The Necromanser of Vas" of the Fighters Guild (http://www.uesp.net/wiki/Morrowind:The_Necromancer_of_Vas) you have to kill a necromancer in Vas with the help of Ulyne Henim. The problem here, Henim can die and if he´s dead you cannot finish the quest, even if you killed the necromancer. Because to finish the quest you have to talk to Henim after the necromancer was killed - but you cannot, because he´s dead too :)
So maybe it would be better to make him immortal, or the quest should end after killing the necromancer - even if Henim is dead too.
For now I was just using console - "Resurrect" on Henim to finish the quest.

#1
You do not have to talk to Ulyne to finish the quest - you should talk to Percius. BTW, Ulyne Henim is a female.