This is really weird... for the last year, all of our users have logged onto the server via Remote Desktop Connection without issue. This morning, none of our users could log on. Nothing has changed, passwords are set to never expire, users cannot change their passwords, and all users are a member of Remote Desktop Users. The only way I can get them to log in is to make them a member of the Administrators group. No Microsoft upgrades have been installed for months nor have any new programs been installed. Any ideas on why this happened or how to prevent it from happening again would be greatly appreciated.