Registry Question

Hello,

 

I use Norton 2012 Internet Security.  I did a cleanup using Ccleaner and found the following listed in the Registry:

 

 

Unused File Extension,  HKCR\ NortonAntiVirus.OfficeAntiVirus.1

 

 

Why is it there?  I'm not using Norton AntiVirus.

 

Thanks,

 

Cody