Have you tired uninstalling FastFox through the Windows Control Panel?

Fast fox does not appear on control panel as "add and remove programs"

Is this the FastFox you are referring to?
http://www.nch.com.au/fastfox/index.html

Or is the Fast Fox not the true name of what's causing your problem?
Might you have Fasterfox installed?
https://addons.mozilla.org/en-US/firefox/addon/rsccmanfasterfox/

Or FastestFox?
https://addons.mozilla.org/en-US/firefox/addon/fastestfox-browse-faster/?src=search

Or FastestFox? https://addons.mozilla.org/en-US/firefox/addon/fastestfox-browse-faster/?src=search

THIS MIGHT BE THE ONE

That is an extension installed in Firefox. Uninstall or disable it via the Addons Manager > Extensions tab.

In order to uninstall a possibly unwanted extension, please do the following:

1. From the Firefox window click the Firefox button at the top left and select Add-ons, or, if the Firefox button is not shown, click the Tools menu and click Add-ons.
2. Once the Add-on Manager has opened in a new tab, click the Extensions button on the left side of the window.
3. You should now see a list of your installed extensions on the right side together with buttons on the right side of each extension.
4. To remove an extension from Firefox, simply click the Remove button. You should see a message that informs you about the successful removal of the add-on.
5. Note that some add-ons require a Firefox restart to be removed completely. To perform a Firefox restart after the add-on removal, click the Restart now link in the message.

You can find further information about uninstalling extensions in the following articles:

Disable or remove Add-ons

Remove a toolbar that has taken over your Firefox search or home page