ERROR : Unable to open your default e-mail folders. The .DLL file for the information service could not be found. MAPI was unable to load the information service Pstprx.dll. Be sure the service is correctly installed and configured.
CAUSE : This problem can occur because Outlook 2002 upgraded the profile once and set a registry key that specifies not to upgrade the profile again. When you revert to Outlook 2000 IMO, choose to use the current profile, and upgrade to Outlook 2002 again, that profile is skipped during the upgrade process.