Mac at risk?

Norton Antivirus tells me that my Mac is "at risk". And prompts me to "Fix now". When I click "Fix now" it will say "Fixing" and "Scanning" for a while and then say "Fix Complete" and "Scan  Complete", but the "Security"- and "Scans"-buttons below will still say "At Risk". I upgraded to 8.3 yesterday and thought maybe Antivirus wants to do a complete scan, but Full Scan ends up saying "Scan Error" (Quick Scan says "No threads found"). Live Update says "Current". 

What do I do?

Yes. I've restarted the Mac several times since it occurred for the first time. 

(And thanks, I wasn't aware of the Mac forum board.) 

 

 

Windows computers often need a system restart to complete software updates. Have you restarted your Mac to see if that helps?

I'll ask this thread be moved to the Mac forum board for better exposure.