I joined the Dark Brotherhood and did 20 DB quests which "should" have given me a reputation of 100. My high skill (shortblade) is 87. My low skill (stealth) is 65. Yet when I was advanced it was only to 5th rank, which means that the game is only seeing a reputation of 50 (or 55).

I have done a batch of other quests as follows:
Mage Guild: 20 quests (I've made Archmage)
Thieves Guild: 20 quests (I'll make Master Thief, 9th rank, in 8 more days...I "wasted" 8 days and checked)
Julianos: 10 quests (I've made 5th rank)
Main Quest: a) Talked with Lady B. Completed Prince Lhotan's quest. c) Lifted the curse on Medora's Castle

Would anyone have an idea as to what "zapped" my DB reputation??????


(I did do 2 quick DB quests, watsed a month, and was advanced to 6th rank.....so yes, it is my reputation that's the problem).
(I'm afraid that if I do more Julianos or Main Quest that I'll zap that reputation even more).

Just in case anybody is interested.

After some experimenting it turns out that my problem was in the "type" of quests I did for the Mages Guild.
Most of the quests (which I did before I joined the DB) were the "guard the dude in a trance" type quests. I suppose that the assassins sent after the guy in the trance were associated with the Dark Brotherhood and when I killed them my DB reputation was docked.

While experimenting I found it interesting that the Mage Guild quest giver addressed me, at times, as Archmage and, at other times, as Punisher (my rank in the DB).