HTTPS crossed out using Gmail
This happens because you're reading an email that containts items (HTML, CSS, images) that aren't referenced from a secure server(3rd party assets/cookies). To eliminate this HTTPS crossed out Gmail warning, turn off cookies in Chrome.
HTTPS crossed out on website
This can happen if the website you are browsing has a public SSL certificate instead of a private one. This isn't a cause for alarm. It just means that the site may be as insecure as a standard HTTP site.
If you're still getting security errors you should make sure you date and time are correct or in sync with the internet time server(instructions below).
Sync Windows clock with internet time server
- Right mouse click on the time displayed in the lower right side of your Windows task bar.
- Select the ‘Adjust time/date’ option.
- Click the ‘Internet Time’ tab.
- Make sure it says ~ “This computer is set to automatically synchronize with ‘time.windows.com’”. Adjust the settings as necessary and save your changes.
Uninstall Google Chrome apps and extensions
I haven't confirmed any particular Chrome apps or extensions that would cause insecure references to files while browsing the web, but you might want to deactivate or uninstall your apps and extensions to double check this possibility.