I did following:

1. Pasted AboutThisMac.nib folder into "/System/Library/CoreServices/loginwindow.app/Contents/Resources".
2. Deleted AboutThisMac.nib folder in "/System/Library/CoreServices/loginwindow.app/Contents/Resources//English.lproj"
3. Logout/Login

Got the same thing ... when I click at Apple/About this mac the screen goes blank and after some seconds my desktop returns ... but I don't get any popup window from About This Mac.
What have I missed ?