Thanks for info. It excluded possibility of Windows XP, IE6/7/8 and so on.
The causes are for Kaspersky to answer. One person in a link I read (forgot the URL) said they were browsing via proxy, and this might be part of the problem. Proxy or 'private browsing' may or may not affect this at all, but it's something to add to the mix if you DO use it.
Solutions (each becoming slightly more complicated or leaving settings disabled):
1. Add trusted domains that cause the pop-up to managed exclusions (whitelist). Presumably adobe.com is above suspicion (as much as any mainstream software site).
If you're getting these pop-ups for pretty much every SSL site, it's going to be a PITA, so I would consider your browsing habits and decide on security levels vs productivity and risks.
e.g. Opera has an add-on called 'HTTPS Everywhere', which attempts to establish "https" to all URLs, but if you encounter a site without an SSL certificate (my own site doesn't have it, nor a need for it), then you get an unsecured connection block, and either get disconnected, or prompted. Again, a PITA.
Kaspersky link - https://support.kaspersky.com/us/common/errors/12489...
2. Add Kaspersky's software certificate manually to your browser - https://support.kaspersky.com/common/errors/13585
Not too keen on this personally, simply because I don't fully understand the implications of control and security around such a move. It might be really sensible, or it might have unknown security implications. I think it's forcing Kaspersky to trust the browser implicitly. Hmm.
3. Disable the scanning of encrypted connections (supposedly for Parental Control, URL Advisor).
I don't recommend this as a first choice, but it 'should' get rid of all further pop-ups. See link 1 screenshots, "Do not scan encrypted connections". If not using or relying on Parental Control or URL advisor, it might be the easiest option.