After installation of E2K service pack 3 only administrators can login to Exchange using Outlook. OWA is fine for all users. Nothing should have changed regarding this during the installation of E2K SP3. The only hits I see relate to RPCs and named pipes but that reg hack didn't help. Any ideas on what to check? AD, DNS and name resolution all look fine. DCDIAG is clean for the DC's in this site. If users couldn't authenticate to AD at all except for Admins I'd know the GC wasn't available, but it appears to be OK and initial logins are not having trouble. But once they run outlook it prompts for all 3 which it shouldn't. HELP !! And thanks in advance for any HELP ! 
