This mypcsecurityreviews.online (so-called Official Apple Support; error # 264D4) has been flagged and blocked by Chrome for Windows.
- Run Task Manager (right click on taskbar) to force that page to shut down - this may result in data loss!
- Block mypcsecurityreviews.online manually;
- Ignore and report this 800-518-9057;
- Switch Safari; make sure you've enabled Microsoft SmartScreen in IE 11 & Edge;
- update your Firefox and/or Chrome, and your Norton for Mac software.