I saw that this error was appearing multiple times on my SharePoint front end server: Event Type: ErrorEvent Source: Windows SharePoint Services 3 Event Category: Database Event ID: 3351 Date: 9/28/2010 Time: 12:06:00 PM User: N/A Computer: WFE2 Description:SQL database login failed. Additional error information from SQL Server is included below. Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp I did some research and it turned out the error occurs because "Windows SharePoint Services VSS Writer" service in that SharePoint box was running "Local System". I changed this to a domain service account and the error vanished.
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