A client called me this morning, reporting that he was unable to use his email.
He uses Microsoft Outlook 2007, and read me this error message:
Cannot start Microsoft Office Outlook, Unable to open the Outlook window.
We tried a couple of different things, but this is the fix that worked for him:
Outlook.exe /resetnavpane
His Outlook 2007 then started OK, and for some reason he had a new folder titled "Unread Messages".