But nowhere I have encountered the problem describing this error code in combination with Windows Server 2008 and Exchange 2007 SP1 with rollup 5.

Well… As I figured out it apparently does not work – if you want OAB to be distributed by Web-based distribution…

You get this error in your Outlook 2007 SP1 clients (on Windows XP and on Windows Vista)

As I can see there is somekind of permission problem becoues OAB virtual directory points to:

C:\Program Files\Microsoft\Exchange Server\ClientAccess\OAB

This directory has NO NTFS permissions for Auhtenticated users… but in IIS there is on this folder a parameter: Pass-through authentication - but as I know it can not work becouse your credentials are not covered in NTFS permissions of that folder.

But it does not work even if you give NTFS permissions to authenticated users… (you are still prompted for username and password in Outlook…)

Maybe I am missing something but weekend is almost over and my users need to use Exchange and RPC over HTTP(s) feature in their Outlooks tomorow… What I did is that I disabled Web-based distribution of Offline address book and I left only Public folder distribution. It took a couple of minutes for autodiscover.xml to update and Outlooks to get new parameters about Offline address book distribution.

Everything works correctly now…

Comments / suggestions appriaciated…

PS.
Hey all you Exchangegurus!
I think you will find this link useful: https://www.testexchangeconnectivity.com/