Problem with website's security certificate (Error "Security certificate not valid")

If you get a message that the website's security certificate has expired when trying to access a certain website, and the time and date of your computer are set correctly, then it's a website-related problem.

If it's a website you have visited often, without any problems, you can contact the website's administrator to report the issue.  The owner or the operator then contacts the certification authority to renew the certificate in order to continue using it.

Note: Avoid visiting websites with an expired certificate. An expired certificate means that the certification authority is no longer reporting on the integrity of the certificate and that it could be stolen and used by a malicious website.

If you get security certificate error on a website you visited many times before, without problems, then maybe you simply typed in the wrong URL.

Try typing it again to see if that resolves the issue.

If you get the error message "The security certificate presented by this website has expired" or "is not valid" , your computer's time/date is set incorrectly. All certificates have an expiration date so if the date on your computer is not set properly, your web browser will think the certificate isn't valid.

Therefore, check time and date on your computer, or reset the clock:

• Windows

1. Click on the time and date in the notification area in the bottom right-hand corner of your screen
2. Click on (Change) Date and time settings
3. See if the clock is set right and change it if it's needed

•  Mac OS

1. Click the Apple menu -> System Preferences -> Date & Time
2. Set the correct time and date
3. Save the changes

Please note that you can always enable the auto-time-update option so that the time and date update automatically.

The CMOS battery makes sure the chip can store data even while the computer is turned off and not hooked up to power. If the battery goes bad, the chip will lose all the information stored on it, and one of the symptoms is that your computer doesn't keep the time and date, and you need to set it up every time when you turn on the computer. If this is the case, you should change your CMOS battery.

Note: Don't replace it on your own if you are not a tech geek, because you might damage the slot which holds the battery tight. Instead, ask a IT-minded friend to replace it for you, or take it to a computer store.

Your computer may simply be set to the wrong time zone and every time you fix the time it resets itself to that time zone when you reboot. Simply change the time zone.

To change the time zone:

• Windows

1. Click on the time and date in the notification area in the bottom right-hand corner of your screen.
2. Click on (Change) Date and time settings
3. See if the clock is set right and change it if it's needed.

• Mac OS

1. Click the Apple menu -> System Preferences -> Date & Time
2. Click on Time zone and select your own
3. Save the changes