Felix, I will settle by running each version at each given time. Thank you very much for the link which is very interesting. Thanks again to all who have answered. I have now the two versions of Firefox running perfectly. Roberto ------------------ Felix Miata wrote: > >That's not a problem, but if you want to run more than one at a time, >you'll need multiple profiles, and a special environment variable set. >See: >http://developer.mozilla.org/en/docs/Debugging_Mozilla_on_Windows_FAQ > >