Is it an extension from the add-ons site? You can try turning off Firefox's version checking and see whether it works in Firefox 7. You do this with (what else) an add-on: [https://addons.mozilla.org/en-US/firefox/addon/add-on-compatibility-reporter/ Add-on Compatibility Reporter :: Add-ons for Firefox] After you install this add-on and restart Firefox, there will still be a message that "--- is incompatible with Firefox 7.0" but the add-on will be enabled and a Disable button will appear for that entry. Does it work? If the program is an external program, then the above probably isn't relevant... ''Firefox 6 is available on the FTP site, but due to security vulnerabilities, it isn't recommended for normal browsing.''