The following solution might not be Microsoft recommended or supported.
Please read the rest of the thread below before tying this fix. There are many other more common fixes to the problem that should be tried before the fix presented here.
I found this solution on a third party web site. The site claimed that it only affected exchange 2007- and prior to SP2. It should not affect Exchange 2010, but in my case it worked. I’m guessing in my case, the in-place upgrade had something to do with it, and I think the problem didn’t appear until the DC was changed to 2008.
In IIS, I changed the ‘Windows Authentication’ to run ‘kernel-mode authentication’
On the client, I was no longer prompted starting outlook. Using the test auto-configuration showed it found via SCP and http status 200. Viewing the Outlook diagnostic logs (olkdisc.log) also showed successful authentication negotiation. Accessing Out-Of-Office failed, as did Free/busy.
On the client, I was no longer prompted starting outlook. Using the test auto-configuration showed it found via SCP and http status 200. Viewing the Outlook diagnostic logs (olkdisc.log) also showed successful authentication negotiation. Accessing Out-Of-Office failed, as did Free/busy.
I then turned on kernel-authentication on EWS and OAB (OAB inherits the setting from the Default Web site level).
Problems with OOF, Free/Busy, downloading OAB all went away for both Outlook 2007 and 2010. Viewing the Outlook diagnostic logs confirms they are successfully running. And I no longer get any authentication prompts.
Thanks for all those who help in troubleshooting the problem and I hope others will find this information useful.
