Security alert on Yahoo mail

Hi, I will start by saying I am computer amateur. Today I have started to get a security alert box after I have signed in to Yahoo mail. It says-

The identity of this website or the integrity of the connection cannot be verified.

There is then a green tick for The security certificate is from a trusted certifying authority.

Then a green tick for The security certificate date is valid, then a yellow exclamation for The name on the security certificate is invalid or does not match the name of the site.

The certificate was issued by Verizon Akamai Sureserver to a248e.akamai.net dated from 27/8/2015 to 27/08/2015.I use IE. I hope I have given enough information. I  would be very grateful if someone may have some ideas on this.

Many thanks.