I've probably played over 500 hours combined between Morrowwind, Oblivion, and Skyrim, but I haven't finished the main quest in any of them.
So easy to get distracted with side stories, putting off the main quest till the absolute end, because you want to savor it, then never doing it ... then your game bugs out in an unfortunate quick save while you're infected with vampirism, and the last manual save was over 10 hours prior (Oblivion).
That's so funny. I had that vampirism in Oblivion and was so mad as it screwed me up when going to sell crap in town. I don't know how many hours I have in Oblivion and Skyrim but, let's just say it's a lot :D
I was able to get around that one through illusion magic or something I think.
Aside from getting stuck in a bad save / quicksave, the part I was most annoyed by was when you get cured of vampirism, and the facial distortion doesn't go away. Only a cosmetic bug, but at the time it really bothered me.
I need to get a hold of my buddy I lent Skyrim out to so I can play this game again.