I have updated to Avast v 2014.9.0.2006
Then noted that a web page that contained links to Amazon books would not load fully - the page's main headings were there but all the book 'icons' that could be clicked on to go to any particular book on Amazon were missing and the page was basically left blank.
After I disabled the plug in that Avast had added to Firefox (Avast Browser Security & Web Reputation) the page loads correctly. Somehow the Avast plug in is blocking the Amazon content from loading.
Any way around that or I may switch AV's and I don't want to do that.