An application cannot read stream data from an encrypted file on a Windows Server 2008-based computer or on a Windows Vista-based computer
Consider the following scenario. On a Windows Server 2008-based computer or on a Windows Vista-based computer, you use an application that has the backup permission enabled. The application also uses the BackupRead API function to read stream data from an encrypted file. In this scenario, the application cannot read the stream data from the encrypted file. Additionally, the GetLastError API function returns the ERROR_ACCESS_DENIED error value.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB952696.