Hi... Outlook 2007 on XP Pro and/or Vista Ultimate.

When I start Outllok 2007, the Outlook Today comes up by default. My data
shows for a few seconds, then it just dissappears. The Outlook Today screen
still shows properly, it just doesn't display any data at all. Everything
else works and displays properly in Outlook. I have not been able to solve
this... any ideas?