Norton Safety Minder Popup

I have the message below appearing on screen as a popup but I suspect it is not genuine.  I always click 'No' and it goes away for a while but always comes back.  It has been coming up for a couple of weeks despite the PC being shutdown frequently.  Is it genuine (therefore should I click 'Yes') and if not, how do I get rid of it permanently? 

 

Norton Safety Minder has updates for this computer. A restart is needed to install the updates.  Click “Yes” to install updates and restart this computer or “No” to update later.  Do you want to restart now?

 

Thanks, Alan.