How to handle messages "This connection is Untrusted" at firefox

Several times I tried to log into some sites like Facebook etc. His views are always annoying as below;

and I try to do the following to overcome the above message

1. click I Understand the Risks
2. then click the Add button Exception
3. then came the Add Security Exception window
4. click on Get Certificate
5. then finally click the Confirm Security Exception button

The next page will load normally and you can go to another web page or facebook. But the weakness of this method is not permanent, because when you log in again then have to repeat the step as above.

After the probe was in another pc results in a smooth current network only. And the conclusion is the problem of not fitting in my computer time with local time.
So I suspected this was the cause of why always come out a message This connection is untrusted.

This case not only when it will login on facebook, but on other websites that use the https when going to login, such as logging in to yahoo, blogger or other websites.

Can also use the 2 way to solve this problem permanently.

- Match the time on your pc with your local time, for that you can go to control panel ==> then select the date and time.
but for some cases you can not set up the time and get out the message "you do not have privilege-level change system time"
if you have this, try searching the start menu ==> run ===> then type gpedit.msc
then try to follow these steps
Local Computer Policy | Computer Configuration | Windows Settings | Security
Settings | Local Policies | User Rights Assignment
then click Change the System Time, to default permissions for Power Users
and Administrators. if the right column to empty time setting, do the add with the click add user / group and then click advanced then click find now. select the user administrator or user that you're wearing now.

then restart your pc and you can again set up the time / clock on your computer.
why can until the time the disabled, it seems this is the work of malware / viruses. Make sure the first scan with the anti-malware and anti-virus updates for more optimal.