MIcrosoft Outlook 2003

Running WIndows XP. Used WIndows 2000 okay and tried to upgrade to WIndows 2003. INstalled and reinstalled it many times. All programs except Outlook run fine. When I try to start Outlook 2003 get the message Cannot start Microsoft Outlook. Unable to open Outlook WIndow. The set of folders could not be opened. Outlook then quits. Help!! M. Menaker