I have a 2008 R2 server with Exchange 2007 SP 3 and IIS 7. I am not using any external mail such as Outlook Anywhere.
All my client PCs use Outlook 2007.
When I open Outlook I get prompted for a username and password. I can cancel it and everything works fine, however when I go to open Out of Office Assistant it prompts me again. If I enter the correct domain user and pass then it lets me in with no problem. My EWS virtual directory is using both basic and Windows Authentication when this happens. If I disable basic authentication on the EWS Virtual Directory then I am not prompted for a user and pass, however the Out of Office replies with, "Your Out of Office settings cannot be displayed, because the server is currently unavailable. Tray again later.”
I have recreated the Virtual Directories, and still have the same issue.
Any help would be greatly appreciated.