The Security Certificate Has Expired Or Is Not Yet Valid” When Try To Enter Websites In IE8:
If you are getting a message popping up on certain web sites when using IE that says “The security certificate has expired or is not yet valid, you will want to check the date and time your computer is set to.
Step 1: Set the Date/time correctly
a. Just double-click on the time in the lower right corner on the Taskbar and set the time correctly.
b. Be sure to check the time, month, date and the year. As soon as it is corrected, this will usually fix this issue.