ErrorZilla Mod is a free extension for Mozilla’s Firefox Web browser that updates the domain access error page, or “server not found” page with some useful tools to aid with troubleshooting. Implements a useful error page when a website cannot be reached. Will add Try Again, Google Cache, Coralize, Wayback, Ping, Trace, and Whois buttons, along with the Firefox logo to the error page when a website isn’t found or a web server is down.
Download this add-on here: https://addons.mozilla.org/en-US/firefox/addon/errorzilla-mod/
As an added bonus, you can get a free and complete Mozilla Firefox, Thunderbird, Sunbird, etc. Easy Backup program called MozBackup. Download MozBackup here: http://mozbackup.jasnapaka.com/download.php