In most cases this error cause due to the corruption in Navigation Pane settings file that block Outlook from starting successfully, so to resolve this problem implement the given process:
In Win XP, VISTA, 07 and 8 you should open the Run command by clicking Win+R and type outlook.exe /resetnavpane in the run command box and after that your MS outlook get open.
If after that you will not able to open MS Outlook PST file, then your MS Outlook PST file got corrupted and you have a need to repair your PST file with the help of the scan PST tool.
For info check this:- http://support.microsoft.com/kb/272227
With Scanpst.exe tool, you can fix Outlook PST errors without any hassle. You can also try a third party Outlook PST repair software, which can repair corrupt PST file and recover data.
To get further information, visit: https://www.emailskb.com/resolved-outlook-is-not-responding-error/