This is for those who are unsure how to deal with the warning messages that some website hosts have appear due to SSL Certificates. Here's how to resolve the issue on Mozilla Firefox.
Go to your sites cPanel login, e.g. yoursite.com/cpanel. You should see this message appear.
Press 'I understand the risks', then some text will appear. Press the button that says 'Add Exception...'.
Firefox should automatically fill this part out but if it doesn't enter the cpanel url into the Location box, make sure the box for 'Permanently store this exception' is ticked and then press 'Confirm Security Exception'.
You should then be directed to the login page where you'll see the username and password box.