It sounds like you may have a serious malware infection. I am going provide you with a couple programs to use (their logs will be essential to others with expertise in the malware arena to give you the help you need).
Please download and install MalwareBytes Anti-Malware leave the defaults in place during the installation process; once installation is completed do a full scan and fix any problems the program finds, make sure to save the log file to the desktop you'll need it later.
Once that is done download and install Super AntiSpyware also leave the defaults in place during the installation process, once the installation is complete perform a full scan with this program and fix any problems found. You'll recieve instructions on how to get to the logs files of this program if they are needed.
The evidence presented indicates a malware infestation that is why the other two programs are needed. If they find nothing then a malware expert will be able to determine whether or not Norton has come across a false positive but it is unlikely.
Please go ahead and use the programs I suggested; this will provide more information to be used in troubleshooting your issue.
I know it's not the best case scenario but the more information we have the better help you can be provided with. I will help you as long as I can and if need be escalate your issue for you.