We are using Umbraco 7.10.1 with Active Directory for login.

We have a user who was logging into the site and editing pages just fine. Then one day she couldn't log in (I don't know the full details as to why), so she changed her password via the Umbraco change password feature (which we plan to remove), but now she cannot login at all.

Her Active Directory login is still working, so the problem is limited to Umbraco.

Then we tried deleting her account and recreating it. When she first got the new user invite, she was able to login successfully. Yay, problem solved! Then the very next day she couldn't login. Again limited to Umbraco, but this time she did not change her password.

Any ideas on how to resolve?