Cannot remove a Trojan called label_parcel.exe. What do I do next?

Hi there,

 

I've just run my weekly antivirus scan and been told that Trojan.gen known as label_parcel.exe exists. The automatic removal has failed, and I've been told to remove it manually. When I try to do this that also fails. I presume Norton knows about this, as it has been identified, but why won't it remove it, and what do I do now?