Netgear WNR2000v3 Problem on Network Map

When I look at my Network Genie, and view my network map, I have two computers showing attached to my router. Both are mine (I only have one actual computer) and one shows a file on it that says ‘share file’. I do NOT want to share any files so how do I get rid of that second computer icon and insure myself that no files will ever be shared? And yes, I know I have to click to share, but I do not want to take chances! And what is difference between public and private settings? They make no sense to me the way it is stated under Network Profile. Public is hidden but private is not?