This has happenned twice in the last 5 months since I installed ArcGIS for Server 10.1. I use "Windows Domain" for User Store, and "ArcGIS Server Built-in" for Role store. The authentication tier is GIS Server. This morning, the AGS server seemed to lose the connection to Windows Domain (AD). I can not login the Manager with my Windowss credential. Fortunately I have not disabled the primary site admin account yet so I logged on using the primary site admin. But inside the manager, I can not access the "Security -> User" tab. I tried restarting the AGS server, rebooting the server, no help. But after I reset to User Store back to "ArcGIS Server Built-in", and reset it back to "Windows Domain", everything started to work fine. Anybody know why? I definitely do not want this to happen again. I am at ArcGIS for server 10.1 SP1.
Allen