Outlook 2007 (temporary .pst file)

I have outlook 2007 installed on 2 computers and have them both accessing the same .pst file.

The problem is when one computer opens Outlook a temporary file is created, when I exit Outlook the temporary file is not deleted and then I can't open Outlook on the other computer because it says it can't open the .pst file.

My question is - how do I get Outlook to delete the temporary file when I exit?

Thanks in advance for any help