Problem
Running a Granular Restore Technology (GRT) enabled incremental or differential backup of a Sharepoint content database hosted on a SQL 2000 server may fail with an error related to Advanced Open File Option (AOFO).
This error occurs even though all backups are run with AOFO/VSS enabled in the backup job.
 
 Error
The last Full backup on database WSS_Content was a streaming backup. Block level incremental and differential backups require a VSS snapshot Full backup
 
Workaround:  Perform full backups only.