1. Open the security editor (either through application or VS menu item)
2. Select User node
3. Add a User

A message comes up saying that credentials cannot be verified. The edit window does come up, but immediately wants to close and asks if you want to save the data. If you click Cancel, you can go ahead and add the user.

This doesn't happen when you try to edit a current user or if you try to add one of the other items (roles, etc).