I have had this problem too. I fixed it by changing the bDrawLandShadows=1 line in the SkyrimPrefs.ini to bDrawLandShadows=0. I don't know if this has been resolved yet or not, but here is what worked for me.
Curse of Hircine is a good mod, if you want to be a werewolf. And Legends of the North is also a good treasure hunt mod. If you like horror there is the Crimson Queen