Hopefully this can help someone else...
After countless cursing the original bug (the missing diary and inability to level up), then the re-install bug (inability to not level up), and then the lack of support (see user is only poster on this issue), I solved my problem. Turns out I had multiple issues. I lost the diary before I ever installed any mods to the game (apparently an older version had a diary bug that was fixed in later releases). Once I figured out I had no diary, I added one using the console command. However, It never worked as it should, and I had to guess as to what XP points I should be leveling. I guessed wrong and had many left over xp points when I installed an updated Nehrim to my new machine, while porting the older save game. This "fixed" the diary bug while porting in the new diary as well. So I had two diaries, neither of which worked. So I was stuck unable to stop leveling up, with the Mehrunes Dagon ability effect permanently attached to my character.
To solve this issue, I followed these steps.
1) I loaded my save game without any animation mods active and saved in a new slot. I noticed that when I loaded the old game without the animation mods I had two diaries.
2) I exited the game, launched the game again and loaded the new save, then opened the console (~)
I entered this command: player.removeitem 00000b96 1 (this removed the second diary)
3) then I entered the console command: set startglobal to 1 (I think this kicks off the script that activates the diary) I was then able to use the diary to level about 6 more times and then the level up icon cleared!
4) there was much rejoicing.
