I am running Outlook 2007 connected to SBS 2003. i have my mailbox and the mailboxes of all my employees. After a certain amount of time, I can no longer view the emails in the additional mailboxes. ie. Can't see it in the preview pane or open the email. I get "cannot open this item". Sometimes it's OK after restarting Outlook. Most of the time, it requires a reboot. This happens 6 times a day now.
My mailbox works fine.