A certificate error message in Internet Explorer is designed to pop up when the browser detects a website's security certificate contains invalid information.

This message appears to protect Web surfers from malicious websites that can download viruses or fake websites set up to gather personal information. But sometimes this security feature goes awry and begins to block trusted sites that the user knows are safe.

To resolve this, check to make sure the date and time on the computer is correct. Often, adjusting the clock settings can fix an invalid certificate error.