We have an exchange 2007 server running a Windows server enterprise 2008 64bit. We had a 2003 domain controller that we recenelty demoted. Once we demoted the 2003 domain contoller users started getting prompted for their username and passwords in outlook. This seems to be random but it does through an error in the Exchange server system log. The digitally signed Privilege Attribute Certificate (PAC) that contains the authorization information for client username in realm DOMAIN.LOCAL could not be validated. We have verifed we have ipv6 enabled. We have verifed the time on both the 2008 dc and the Exchange server are synced or are within 1 minute of each other We only have a single domain so this is not a trust issue. I have researched this issue and have had not luck. Any help would be great. Thanks, Chad

Hello, Is there any update?Fiona Liao TechNet Community Support