This might seem like a small problem to solve for a customer, but I think I have googled and tried most fixes out there, might aswell start back from scratch as there are obviously something I have not picked up.
The server is a SBS 2008 with Exchange 2007.
The clients are Windows 7 with Outlook 2010.
The clients are domain-members and users are logged in with domainuser-accounts for the exchange-account.
There is an external approved SSL certificate that matches the FQDN for the IIS-webapplication-site.
The problem is occational popups (several per hour) prompting for authentication for Exchange.
Outlook is only used on workstatsions in internal LAN for this domain, not external usage.The domain name is correctly configured and E-mail flow in/out is working properly.
In addition symptoms Outlook wont load global address-book on demand, and the test for autoconfig fails even after it actually autoconfigures a new profile in Outlook.
Problem started early last month, and I have done most of the basic stuff as looked at the IIS Authentication for the related webapp folders, enabel kernal-mode auth, made sure all updates are installed incl "Rollup 10 For Exchange 2007 SP1".
I have also temporarily turned off Outlook Anywhere proxy in Outlook on a client but no luck, same auth-popup...
Where can I go from here?