Hello cheriann1961, boot the computer in [http://windows.microsoft.com/en-hk/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7 Windows Safe mode with network support] (press F8 on the boot screen) and then see if that allows to download and install Firefox from the next link : full installer/all languages : https://www.mozilla.org/en-US/firefox/all/ Probably your security software (firewall, anti-virus) blocks firefox. Try to remove all rules for Firefox from the permissions list in your firewall and let your firewall asks again for permission to get full access to internet for Firefox. thank you

Network Proxy Type '''about:preferences'''<Enter> in the address bar. Select '''Advanced > Network.''' Look for '''Configure How Firefox Connects''' and press the '''Settings''' button. Check the settings.