Did you just find something called Site Matcher Pro in Mozilla Firefox’ Add-on dialog? 
Site Matcher Pro is a piece of software that suggests similar web site based on the sites that you are currently browsing.
How did you get Site Matcher Pro on your computer? I found it bundled with an unofficial Adobe Flash Player download. The Flash download was signed by the SuperCool Applications publisher. Here’s a screenshot of Site Matcher Pro appearing in the installer:
If you’d like to remove Site Matcher Pro, you can do so from inside Firefox, or by selecting the Site Matcher Pro extension for removal in FreeFixer:
Hope this helped you to figure out what Site Matcher Pro is and how to remove it.
Update 2014-10-06: Found Site Matcher Pro in another installer:
18.07.2014 Firefox pop-up dialog:
This ads cause security risk.
I can’t remember that i install it by myself.