Just received email of new version
Introducing CCleaner v5.44
Tried to install and Norton said "NO" blocked what it said was a dangerous download.
when I had Nortons, I got a similar issue when download MBAM updates.
just add it to Nortons exception rule list.
it's probably detecting the embedded offerings of Chrome and/or Avast and/or the new ads pop-up system.
Can you confirm exactly which Norton product you are using? I need to file a False Positive report and it's a bit bureaucratic.