Unresolved threat keeps coming back

My elderly father has a Windows Vista laptop and just had Norton Security installed remotely by someone from Norton.

For the past week or so, he is getting a pop-up about a threat that needs a reboot to resolve. He has rebooted numerous times, but the message will not go away. I did a bit of research yesterday and went in and removed everything that was in the quarantine. After that, I cleared the one unresolved threat (photo attached). After doing so, it came back. It just will not go away. Is this some type of malware infection? A glitch?

 

Dave