Microsoft Outlook users have complained of receiving an error saying “We cannot start Microsoft Office Outlook. Unable to open Outlook window”. After running Microsoft Office Diagnostics to resolve this, users will receive a message saying that there are no errors. This leaves the user without any solution to the problem, and they cannot open Microsoft Outlook to send or receive emails. This problem is caused by a corrupt .xml file (which is used to store your personal settings for the Outlook Navigation Pane) and can be resolved as follows:
• Use the / resetnavpane switch:
Close Outlook. In the Start search field in Vista or Windows7 Start menu or in the Start menu, Run command (Windows key + R), type “outlook.exe / resetnavpane”
Also, when following the above mentioned procedure, it is advisable to make sure that there is a space between the words.
After entering the correct command line, you need to press Enter (or OK button) to restart Outlook. Your navigation panel will be reset to its default settings, that is, without any personal touches such as your favorites.
• Delete the navigation panel configuration file: If you have problems with the switch, you can find and delete the XML file that contains the navigation panel parameters. In the Start search or Run fields or in the Windows Explorer address bar, paste the following and press Enter:
% appdata% Microsoft Outlook
This opens Windows Explorer to the folder where most of the Outlook configuration files are stored. Find and delete the named file for your profile with the XML () extension. It is recommended to use the switch instead of canceling the switch directly.
Once you have completed one of these steps, your navigation panel will be reset, and you will no longer experience the above error. However, all customizations you made in the navigation pane will be lost and will need to be redone.