I am not familiar with Norton alert windows, but those might be fake. Something just doesn't look right about them.
Have you considered using something other than Norton?
I would download and scan with Malwarebyte's Ant-imalware.
It's free and very effective.
Malwarebytes

Personally, I would uninstall Norton and download something like Avast or Microsoft Security Essentials.

I would:
- boot the computer in safe mode with networking
- download to the desktop and run smitfraudfix Official SmitFraudFix Page
- after that, download Malwarebytes and do a full scan
- after that, reboot in Windows normally
- uninstall Norton
- Install Avast, Avira or Microsoft Security Essentials, update, then run a full scan.
- check for and download Windows updates