Outlook 2007 Shut down Problem

[Oilcan]

When I try to open Outlook 2007 (Office 2007 Professional) I get the message:
Outlook did not shut down properly...and then it goes into a Detect and
Repair but it never finds a problem. I have also ran Office Diagnostics
which did not turn-up any problem. I am running Vista Ultimate 32 bit.

Thanks in advance for any ideas of what the problem might be.