why did message the certificate expired appear on screen?
Ensure that the time, date, and time zone are set correctly. If the time and date on your computer is incorrect, you may receive the message The security certificate has expired or is not yet valid.. To resolve this issue, ensure that the time, date and the time zone are set correctly.
The certificate error message may occur when using Yahoo in Internet Explorer. This can be fixed two different ways. 1  Computer's date is incorrect. 2  The security certificate has expired.  The website is not trustable.