Lots of Med Risk Unauthorized Access Targeting Norton

I've recently been getting tons of Medium Risk Unauthorized access targeting NIS.  The log always says actor is c:\windows\explorer.exe  with actor PID of 2204. This started after getting a strange popup while in IE regarding a virus or malware which I closed without clicking - I then closed IE and immediately did a full system scan which found nothing. 

 

System performance doesn't appear to have been impacted but I'm concerned over the high number of unauthorized access attempts.  Should I do a Hijack this scan and report the log here?

 

Thanks for any advice.