It sounds like you ran into a bug with those quests. <img src="/ubbthreads/images/graemlins/disagree.gif" alt="" /> It is possible the items were placed so they were obscured by a wall, or something, where hitting the alt key would not necessarily display the description. Boss monsters might have been placed outside of the third level where you could not reach. If you don't want to re-check the third level of all 6 dungeons, you can just leave the quests unfinished.
