"g1mail" wrote in message
...

I recommend you to use a real "backup" tools like BackupMyFolder! that
will be able to backup PST files while Outlook is running, and as the
backup is an incremental backup, the backup time is very short.

It's just not possible to get a reliable backup of a PST while Outlook is
running. Outlook holds some data in memory until it closes. That data will
be missing and the PST you do manage to back up may be internally
inconsistant.
--
Brian Tillman [MVP-Outlook]