http://uk.norton.com/downloads-trial-norton-antivirus
http://buy-download.norton.com/downloads/2013/20.1/NISNAV/UK/NAV-TW-30-20-1-0-24-EN-UK.exe
should be
http://buy-download.norton.com/downloads/2013/20.1/NISNAV/EN/NAV-TW-30-20-1-0-24-EN-UK.exe
spot the difference (UK should be EN, it has to be Upper case) as the NIS and 360 are EN in the links
I have reported this post as well so mod admin can notify the site admin to fix it (been like that from when 2013 NAV came out so it needs fixing as its unprofessional for an antivirus site)