On every SharePoint web front end use the Local Security Policy snap-in
(Start >
All Programs > Administration Tools > Local Security Policy) to confirm that
the SharePoint application pool accounts have the following privileges on each
SharePoint web front end:
- Act as part of the operating system privilege.
- Impersonate a client after authentication.
Note: If the two changes above for the application pool account are not
acceptable for the the application pool account used by regular users, consider
extending the SharePoint web application and using a separate application pool
account for the extended web application. Then when
Adding a SharePoint Location, use the original web application for
the External SharePoint Location URL and the extended web application URL as the
Internal SharePoint Location URL. It is the Internal SharePoint Location URL
that must use an application pool account with the specified
settings.