RE: Uninstalling Messanger PlusSmartbar
The Messenger Plus! Smartbar has a very clear Firefox add-on entry:
If for any reason this extension/add-on remains after Smartbar is removed from add/remove programs, simply Go to Firefox / Tools / Add-Ons / Extensions pane, Remove this extension and restart Firefox browser.
Once removed, it wonít (and canít) come back unless the Smartbar is reinstalled.