Click the Firefox button, go to Add-ons, then Plugins. In there, disable "'''My Web Search'''". This is an adware which probably came bundled with a 'free' app you installed at some time or another. It runs silently in the background searching for ads to feed you. ---- In addition, update your Flash installation. The version you have at the moment exposes your system to exploits. See http://www.adobe.com/support/security/bulletins/apsb11-12.html Link to the update at the foot of the page in that article.