Why is Norton 360 blocking my site

My site has a clear safe web report, and is clean when put through link checkers. When visited direct or through a link from most social media sites it loads OK but when visted from a link via google plus it is blocked for a "malicious executable download 6"

 

Virus checks on the site are clear and htaccess is not set to divert of site. I've reported it as a false positive but am told it meets the critera. How can I get an answer in plain english what needs to be done to remove this alert. I keep being told how to unblock it in my installation but that's not what I want. I want the site to report clean for everyone and remove this download (even though I don't think it exists.

 

The site is historicnavalfiction.com and the problem is with links when visted from https://plus.google.com/u/0/106881622949263698609/posts