When visiting a website in IE, you get this message:
The security certificate presented by this website is not secure
Normally when there’s an outdated certificate, you get the option to “Continue to this website” anyway. The option to do that is missing if the old certificate is secured with a key that is too small (less than 1024 bits).
To fix this, if you own the website, secure it with a better certificate. If you don’t own the website you have 2 workarounds available. Either use Google Chrome, or change the value of this registry key to be (DWORD) decimal 512: