In Firefox 3.6+ versions you can only have one Theme enabled at a time, whether it be a LightWeight / Persona theme, or a "Heavy" theme like Noia. If you want to use both a Theme and a Persona (light-weight theme) together, you need to install the Personas Plus '''1.4''' extension ''(any other version of Personas Plus won't work that way)''. https://addons.mozilla.org/en-US/firefox/addons/versions/10900 Type about:config in the URL bar and hit Enter, then create a new '''''boolean''''' preference and set the value to '''''false''''', to keep that extension from being updated automatically to a newer version and not work like this any more. Pref = <code>extensions.personas@christopher.beard.update.enabled</code>