Error while opening certain sites - To help protect your security

My question might sound silly to most of you, still I would appreciate if someone could help me

While accessing gmail, I get following message at the top

"To help protect your security internet explorer has blocked this website from displaying conent with security certificate errors"

Although I am able to access my mails but I am not happy with the performance.

Can anyone help in finding out how to fix this error?

Thanks