What is yontoo? is it suppose to be in my add-ons?
Yontoo is a potentially unwanted application that installs a browser extension to display advertisements that appear to be from Facebook. How trustworthy is Facebook in your opinion.
A PUP (potentially unwanted program) is a program that may be unwanted, despite the possibility that users consented to download it. PUPs include spyware, adware, and dialers, and are often downloaded in conjunction with a program that the user wants.
The term was created by McAfee, the Internet Security company, because marketing firms objected to having their products called "spyware": in the view of such firms, all the information necessary for informed consent is included in the download agreement. It is widely recognized, however, that many if not most users fail to read a download agreement in sufficient detail to understand exactly what they are downloading.
Run a full system scan via your Norton product. If that does not resolve the problem you can try one of the Malware Removal Forums eg: http://forums.whatthetech.com/index.php? to verify your system is free of nasties.
<< is it supposed to be in my add-ons?>> Do you want ads from Facebook? Do you want to use Facebook? Facebook and the like need a way to monetize your mouse clics.
If you have Malwarebytes Anti-Malware Free (skip the 14 day trial) installed. Update & Run a Full Scan for a second opinion.
A dedicated Malware Removal Forum working one on one with an expert will verify your system is free of nasties.