I have recently completed the cure for vampirism quest. I have a game saved just before the Count is summoned to give me my reward, and here's where it gets interesting. If I drink my own cure vampirism potion and then summon him (via the Argonian lady), he is no longer a vampire (ie, no elongated canines, skin is more coloured, obviously human again). However, if I summon him and I am still a vampire he is not cured. Has this happened to anyone else? Would there be any consequences to later Janus Hassildor quests if he is cured?

I took a look at http://www.uesp.net/wiki/Oblivion:Janus_Hassildor and didn't see anything that resembles the problem you describe. I also looked at the http://www.uesp.net/wiki/Oblivion:Vampire_Cure#Bugs. I didn't see anything about it there either.

I'm sorry I couldn't be of more help. I've never been a vampire, so I know nothing about vampirism. With any luck someone else will know, though. Good luck.

Thanks mate =) sounds like a bit of a mystery ..

Sounds like a bug to me. Or maybe he steals some of your potion :shrug:

Most likely a glitch. I don't think Hassildor wants to be cured..

There are only two potions from the witch. One is supposed to be used by your character. The other Count H. gives to his wife so she can be cured and die properly.

Whether he wants to or not, he is supposed to remain a vampire.

Because several dialog options have him referring to himself as a vampire, both during the Mages' Guild questline and during the Main Questline.

So if he doesn't appear to be a vampire it appears to be a bug. But it doesn't seem like it will be game breaking. You just might get some dialog about him still being a vampire.

Hm.. It's strange. I thought perhaps he had taken a portion of his wife's potion. Also, when I first receive the potion(s) Malisande tells me "I believe you have promised these portions to another. Come back and see me when you have delivered them and I will give you another" or words to that effect. Leftover dialogue from an earlier iteration of the quest?