Em que sistema está a instalar o Firefox?
[[Installing Firefox on Windows|[[Image:vista.jpg|valign=middle]]Instalar o Firefox no Windows]]
[[Installing Firefox on Mac|[[Image:macos.jpg|valign=middle]]Instalar o Firefox no Mac]]
[[Installing Firefox on Linux|[[Image:linux.jpg|valign=middle]]Instalar o Firefox no Linux]]
Based on information from Installing Firefox (mozillaZine KB)