The issue occurs due to a self-signed certificate connection. You can read more about the nature of certificate warnings here:
1. Open main Kaspersky window - More tools - My network - Network monitor;
2. Sort the table by Port.
3. Find the port 8009 and note down the local IP address used by it (like 192.168.x.x). There can be several IP addresses.
So far this is what has worked for me. I opened the Google Home app on my phone, navigated to the settings for each of my chromecast devices (1 audio & 1 regular) and unchecked the box to send device usage data and crash reports to Google. Then I rebooted each chromecast device and my Windows 7 PC.
Here's what it fixed (so far) but I don't know how long it will last:
It's been 4 hours now since I've had the "self signed certificate" warning from Kaspersky and I've been using th