The message is stating that you're seeing a Captcha because suspicious traffic has come from your network. If you're not doing suspicious things, "check that you're not infected with malware" is valid feedback.
No, it’s because Cloudflare and archive.ph have some pissing content going. I forget the details, but it has nothing to do with malware on anyone’s machine. Somewhere on HN someone has given a better explanation, but I’m not spelunking for it.
No, the message is stating that because I don't allow Javascript to fingerprint and commodify my browser. The euphemized nonsense about malware is just an insult to reason at this point.