Is this about downloading and installing Firefox or using Firefox to download files from internet? Try this in case of problems with downloading or updating Firefox: *Download the full Firefox installer and save the file to the desktop<br>https://www.mozilla.org/en-US/firefox/all.html *Start the installation with a double-click on the desktop icon Make sure that your anti-virus software isn't blocking downloading files or is interfering otherwise. See: *http://kb.mozillazine.org/Unable_to_save_or_download_files *browser.download.manager.scanWhenDone = false