Netbak replicator failing to restore - Outlook files

[JeffT]

Hi community,

I'm hitting a wall trying to restore some Outlook OST & PST files that were backed up by Netbak Replicator. It sees them in the backup okay but when I try to restore, every file gives an error like this: "The system cannot find the file specified.
Ignore to restore file D:\NetBakData\user@pcname\Outlook\QBackOL02.pst.f" (D:\NetBakdata is the location of the backups; I'm restoring to a temporary folder on C:).

What are these '.f' files it's referring to? How can I get my data to restore?

Thanks!

Jeff