Hello everybody (first post). I have an issue with my fresh installed Exchange 2007 SP1. Seems that Outlook 2007 clients, ask for credentials when they try to load OAB, the user enters the credentials and this fails (asks again and again). After that there is an "need password" string to the bottom right of Outlook and of course the last "send/receive" is failed with 0x80048002. The even stranger thing is that sometimes if someone clicks this "need password" (to retry the password) the "need password" string goes away! Here are the data for you: I only have Outlook 2007 clients so I don't know what happens with other versions.Cached or no-cached exchange makes no difference.Setting in Outlook to use Kerberos or NTLM for the exchange connection makes no difference.Autodiscover exists/works.I have enabled OAB also in Public Folders and Web.My internal domain and my external domain is the same (let say mydomain.gr) and DNS entries for mail.mydomain.gr exist) Web link exists (http://mail.mydomain.gr/OAB or http://myexchangehostname.mydomain.gr/OAB) but asks for credentials and anything I enter fails (mydomain\myuser or even mydomain\administrator).This is a pure Exchange 2007 SP1 environment, not migrated.Servers are all quadcore xeons with 2008 SP1 x64 and rollup 6 is in.My mailboxes are very few (about 15 inc. distribution groups). Shouldn't have performance issue, but I've noticed ~7GB RAM taken by Exchange!Seems that if I don't login at least once in the prompt, I don't even get logged in Exchange (not only OAB)!(could be related) There is OCS R2 in the domain and Communicators although login in OCS, they ask for username/pass for my Exchange, no credentials entered work, so I get BOTH "outlook integration error" (with explanation that login dialog was canceled or closed -which is true since no credentials work- AND cannot syncronize address book (again with the same explanation)There COULD be a certificate issue (I have a 3rd party -DigiCert- wildcard certificate assigned to Exchange, with various SANs), I am not sure if THIS is related (but why not OAB which DOES NOT use certs?).Also I don't know if it is related (probably is since I am not getting OAB updates), but I cannot send mail to several INTERNAL users and the system whines that doesn't know them.Public Folder OAB is also set up and in fact I requested even version 2 (old) compatibility. Everything was working before (both Outlook and Communicator) and I am not sure what could have changed.Thank you for your time. It's painful for all the users to have to cancel this requester every few seconds. Yes I've looked all the related threads (I think).

Hi, 1. Open a command prompt and run the following command on any Client Access Servers: %systemroot%\system32\inetsrv\AppCmd.exe set config /section:system.webServer/security/authentication/windowsAuthentication /useKernelMode:false 2. Next, enter IISRESET /NOFORCE After that, please restart the Outlook Client and attempt to download OAB files again. Mike

Thanks Mike.Kernel mode is already off in all IIS tree levels.