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
If Scan PST Tool is fail to recover Outlook PST Data then use a third party tool like MS Outlook PST Recovery tool.