A common access of several programs on one Outlook^® PST file is not possible. Also if the Outlook^® on the “server” is open you can not backup a pst file.

A backup is possible if the “Public ShareFolder Server” (PSF) is stoped. To stop the PSF you can install the PSF as Windows^® service (FAQ Nr. 1) and and you can start and stop the PSF server with 2 batch files. Have a look on FAQ No. 01