Now and them some of my users are unable to login via Outlook Anywhere or Outlook Web Access - I don't have anyone logging in locally to the Domain. It only seems to effect one user at a time, but as to which user it effects varies.The setup is, 3 CAS using NLB, 2 HUB, 2 CCR MBX Clusters 1 Standalone MBX & 2 EDGE servers.When it happens, I can see the following in the IIS Logs of one of the CAS Servers, repeating every 30 seconds or so.2009-10-20 10:00:29 <CAS_IPADDR> RPC_IN_DATA /rpc/rpcproxy.dll exchmbx02.domain.local:6002 443 user@domain.tld <USR_IPADDR> MSRPC 401 1 1909 532009-10-20 10:00:29 <CAS_IPADDR> RPC_OUT_DATA /rpc/rpcproxy.dll exchmbx02.domain.local:6002 443 user@domain.tld <USR_IPADDR> MSRPC 401 1 1909 15It has happened across 2 different CAS Servers, but I've only seen the errorrelate one MBX Server.Anyone have any ideas?

Looks like some authentication issue. Can you check the IIS Virtual directories authentication for RPC.Raj

Hi there,I have verified by using the Get-OutlookAnywhere command that for ClientAuthenticationMethod and IISAuthenticationMethod that Basic is the only one that is enabled for both on all 3 CAS servers.Outlook clients also have the Authentication set to Basic.

Hi, The error 401.1 means access is denied due to invalid credentials. The win32 status 1909 means the referenced account is currently locked out and may not be logged on to. Therefore, when the issue occurs, please check whether the user account indicated in the log has been locked out. ~~~~~~~~~~~~~~~~ Mike Shen TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb @ microsoft.com ~~~~~~~~~~~~~~~~