Why do I have to open Outlook twice for Inbox to populate with new messages

I have to open Outlook 2007 twice before my new messages will appear in my inbox. Take for example if I log out and leave for lunch and come back and log on again and open Outlook there will be no new messages in my Inbox, however I no I received email because they showed up on my mobile device. I did not read them on the mobile device I just saw that I had new messages. So then I close Outlook and wait for it to disappear from the taskbar and then I reopen it and now the new emails populate the Inbox. This happens each time I log off or restart my machine.