Starting at approximately 09:00 on 3rd Dec, 2015, customers began experiencing intermittent issues accessing Azure services that use, or have dependencies on, Azure Active Directory. Engineering teams have identified an Azure Active Directory configuration error that is believed to be the root cause of the issue.
Microsoft provided Business Insider with the following statement: "Some customers may be unable to access our services due to a service incident. Our teams are working to restore access as soon as possible."