I've searched and don't see anything quite like this except I get the Werewolf cutscene and then a fraction of a second of regular game play, going back to cutscene - fraction of a second of regular game play - cutscene . . . forever. The game play part is so short I have to hold down the esc key during the cutscene so maybe it will be recognized when the short game play occurs.
I never have been a werewolf except the mandatory main Bloodmoon quest and I did the cure thing. I did put on the Hircine ring once and didn't like that. I think I even went back to a previous save to make sure that didn't "stick." After finishing everything in blood moon except finishing the East Empire Company quests I went back to the mainland and finished the 4th and 5th trials spending several days and I never turned into a werewolf. I went back to Solstheim and on the dock there was the Odd Note. I thought this was odd since I wasn't a werewolf but I thought what the hell and I did the quest anyway and I got the completely cured and will never become a werewolf ending.
It was after that I started turning into a werewolf, sort of except with the repeating cutscene so you can't play from that point on. It doesn't happen at midnight either. So far it's been 8:30 pm and 10:30 pm. It does an autosave even though I have that turned off (NameWerewolf.ess) and that keeps bumping up my save game number so it's a bit of a drag trying a lot of guessing on how to fix it. I can "show fbmwBmPlayerIsInfectedWerewolf" and it is 0.
Any ideas how to cheat and get rid of this problem. My earliest save game available is after I picked up the Odd Note but before I did the quest and it doesn't look like I'm turning into a werewolf at that point but I'll have to re-do a fair bit and I'd like to figure this out and post a warning. Don't Pick Up the Odd Note If Your Not a Werewolf! Also, I did sell Hircine's ring if that could have done it.
Thanks

The most likely cause is that
The most likely cause is that your savegame script variables are somehow out of sync or not properly updating. This could sometimes be seen in the unpatched Morroblivion v064, but I haven't seen any reports of the repeating werewolf transformation bug in the v065 builds until now. Please post your savegame file and I will try to examine it when I have time.... my only tip for now is to never save or load a savegame which was saved while you are in werewolf form. Good luck.