Certificate help! What should I do?

[marielle d]

This is the message that I get. And sometimes on Facebook.

The server's security certificate is not yet valid!
You attempted to reach twitter.com, but the server presented a certificate that is not yet valid. No information is available to indicate whether that certificate can be trusted. Google Chrome cannot reliably guarantee that you are communicating with twitter.com and not an attacker. Your computer's clock is currently set to Wednesday, August 15, 2012 4:40:39 PM. Does that look right? If not, you should correct any error the refresh this page.
You cannot proceed because the website operator has requested heightened security for this domain.