internet explorer error

I have a pc running Windows XP Professional and Internet Explorer 6. E-mail is working fine but when I click on either the IE icon or the actual executable file I get and error message reading “Windows cannot find ‘C:\Program Files\Internet Explorer\Iexplore.exe”. I have tried replacing the executable file with one I know work but no luck. I even reinstalled Windows XP and still no luck. I have the current version of Norton so theoretically I don’t have any virus, etc problems. Does anyone know how to fix this problem?