I've moved my profile to an external HDD, and deleted everywhere I know that Firefox is located:
C:\Program Files\Mozilla Firefox (OR)
C:\Program Files (x86)\Mozilla Firefox
C:\Users\*username*\AppData\Local\Mozilla\Firefox
C:\Users\*username*\AppData\Local\Mozilla\updates
C:\Users\*username*\AppData\Local\VirtualStore\Program Files\Mozilla Firefox
Plus even the 'roaming' ones, too
AND used the Advanced scan with Revo Uninstaller to remove every other trace of Firefox - registry included.
I've also tried another suggestion that has already been said on here before:
But after [the ridiculously long process of] reinstalling firefox, it worked ONCE [and once only], but after restarting Firefox, the same message appears again!Close all applications and reboot the computer.
Delete any downloaded or partially downloaded installer files.
Clear the browser cache (of whatever browser you are using to download FF) and the Windows Temp directory.
Shutdown any anti-virus software you are running.
Download a new copy of the full installer from http://www.mozilla.org/en-US/firefox/all
Delete the directory C:\Program Files\Mozilla Firefox
Run the installer.
Restart the anti-virus program.
I've ran out of ideas (and running out of patience) as to why it still keeps saying this.
I don't know if it's just because my computer's so old or not, but seems to take at least something like 10 minutes to install it! And to keep on trying to uninstall it and reinstalling it all the time seems to take forever.
Any help will be much appreciated. I don't like the other webbrowsers, and for the time being I'm using the Mozilla-based program CLIQZ - but I can't install any addons to it, as it's a "privacy browser".