I have performed a swing migration from Exchange 2003 to 2010. I'm in the process of decommissioning the old Exchange 2003 server and thought I would just stop the Exchange services before uninstalling to see what happened. After I stopped the Exchange 2003 Information Store service quite a few user's Outlook (various versions) started prompting for a username/password. The password will take for a while but will return and will prompt when launching Outlook. All mailboxes have been migrated to 2010 except for the old Exchange admin account and an old Blackberry admin account. Public folders have been replicated to 2010 and the old 2003 replicas removed, mail flow works well, same for OWA and Activesync, Everything seems to work well other than this annoying Outlook password prompt. One odd behavior is my computer at the office, joined to the domain, (Windows XP/Outlook 2010) prompts for the password when the Information Store service is stopped. But my home computer via a VPN (Windows 8/Outlook 2010), NOT joined to the domain, doesn't prompt for a password. Same user account being used on both machines. Both machines are running Outlook Anywhere. Any ideas?