See this - http://malwaretips.com/blogs/ads-by-browser-good-removal/ If you don't get "stuff" like that removed completely, the next time you open a web browser that it targets or launch your computer cold, that "thing" may just reinstall itself into the browser. "Typically distributed through a pay-per-install bundle or with third-party software (example: CNET installer, Softonic Installer, InstallRex installer and many more)"