That's really odd, given I've found white_teeth to be one of the most stable. Have you tried downloading it manually into your override folder? Could it be a fault with the nexus mod manager?
In my limited experience, White Teeth was very stable, working with pretty much anything. I tried extracting WT to desktop, then moving it into override, and extracting it within override, both were unsuccessful.
NMM I just reinstalled fresh, along with DAO, the pathing had gotten a little screwy, and I wanted to make sure there were no issues. I tested NMM on a beard mod, which wasn't working before, now it's activating amd deactivating fine. It's the most recent version, if that helps.
Edit: BTW, how do I change the thread title? It's a little vague...