My exchange server was rebooted after some windows updates, when it came back up it Outlook 2010 forced a lot of users (not all) to authenticate. This is the first time it has done this. Any ideas on what could have caused this?

Hi timestream, You mean after server reboot, users need to authenticate every time (open Outlook) or only one time? Since this issue not occurred on all the users, do you recreate Outlook profile to have a try? Here is a related thread for you, hope can give you some help: Outlook prompted for password after reboot of Exchange 2010 http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/467ec116-3bf7-4b6e-9705-b8a5fd8191a9 Thanks, Evan Evan Liu TechNet Community Support

Hi timestream, You mean after server reboot, users need to authenticate every time (open Outlook) or only one time? Since this issue not occurred on all the users, do you recreate Outlook profile to have a try? Here is a related thread for you, hope can give you some help: Outlook prompted for password after reboot of Exchange 2010 http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/467ec116-3bf7-4b6e-9705-b8a5fd8191a9 Thanks, Evan Evan Liu TechNet Community Support