Essentials conflict with iTunes – firewall/network connections issues

Hi All, I recently loaded MS Essentials as I was advised this was a better protection than most other anti virus softwares on market.  (previously had McAfee) Since then my iphone5 will not connect with iTunes. Am getting "iTunes could not connect to the iTunes Store.  Make sure your network connection is active and try again'  Apple Support chat line advises that there is a known conflict between Essentials and iTunes around a firewall issue.  Would appreciate any advice/cure, please.