2) When I save the downloaded file, Chrome throws a warning (attached image) that the file is "not commonly downloaded and may be dangerous." That may be because it is new (so not a problem), or it may be because the Publisher is Unknown.
3) When I try to run the file as administrator, I get the prompt to "allow this app from unknown publisher to make changes..." and the Publisher is listed as Unknown (attached image).
You can occasionally see such a browser warning on the first day or two that a new version is out, but 608 has been out for a fortnight now.
(It's more common to see it from certain AV's rather than from a browser).
But even if that happened I wouldn't expect the UAC to show an unknown publisher.
I'm not seeing those messages with either Firefox or Edge.
It downloads normally from your link in both browsers, and when run the UAC says that the publisher is Piriform.
I'd check that your Chrome, and your Windows, are up to date.
If you have installed it anyway then you might want to uninstall it, and then run a virus scan. (Better safe than sorry).
Next:
Try downloading, and then double clicking on, an installer from here: <a href="https://www.ccleaner.com/ccleaner/builds" ipsnoembed="true" rel="external">https://www.ccleaner.com/ccleaner/builds</a>
Download and use the 'Slim' installer which is the 3rd one down there.
It installs the standard CCleaner but it's a slightly different installer.
Let me know if that download also throws any warning for you, or if the UAC doesn't see Piriform as the publisher.
PS. There are fake websites out there, and browser hijackers, so just as a double check:
When you go to<span style="display: none;"> </span> "https://www.ccleaner.com/ccleaner/download" is that still <em>exactly</em> what it says in your browser address bar?
Thanks so much for the quick response! I checked my Chrome and Windows 10 and they are both up to date. I downloaded and ran the _slim.exe installer you suggested. That showed Piriform as the Publisher and installed correctly, so all is good now.
Just to see what would happen, I tried downloading the same file as yesterday (the one with no publisher) and now there are no warnings from Chrome or UAC and it shows Piriform as the Publisher. Don't you just hate those bugs that just go away for no reason? ;)
Odd things do happen and then go away seemingly on their own.
It might have been a glitch in the download process, maybe the server that checks publishers security certificates was unreachable for a minute or two, it might have been a temporary glitch in Chrome's security checks, it might have been ........
Make your own guess because we'll never know for sure.