If you cannot open Microsoft Outlook 2007 and get the following error: “Cannot start Microsoft Outlook. Cannot open the Outlook window.” after previously being able to open it, then you might want to try the following:
Go to Start > Run and type the following: “outlook.exe /resetnavpane” (without the quotation marks) and press Enter.
This should fix the problem.
The “/resetnavpane” Outlook command switch clears and regenerates the MS Outlook navigation pane for the current profile.