I added an add-on but I no longer want it.
In order to uninstall a possibly unwanted extension, please do the following:
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
There are other things that need your attention.
Please Update to the latest Firefox 17.0.x version.
The Firefox Firefox 8.0.1 version that you currently run is no longer supported with security updates