My outlook 2007 looses the mapping to my local PST file after reboot.

I have Outlook 2007 running on Vista, I have several local PST files that I use for archiving emails from the server. I have connected the pst files to the outlook client and everything seems fine. Then when I reboot and log back in the PSTs are not there or have been changed. Very weird, it creates a series of files with the first word from the pst filename that appear to be empty.