untrusted connection

it used to work fine up until a couple days ago how can i fix it

This Connection is Untrusted

      You have asked IceDragon to connect

securely to www.facebook.com, but we can’t confirm that your connection is secure.
Normally, when you try to connect securely,
sites will present trusted identification to prove that you are
going to the right place. However, this site’s identity can’t be verified.

      What Should I Do?
        If you usually connect to

this site without problems, this error could mean that someone is
trying to impersonate the site, and you shouldn’t continue.


Please run IceDragon in Safe Mode to check if any add-ons are interfering with your connection.
You can also disable Comodo DNS in Options>Advanced to check whether it solves the issue.

Thank you.