I have 2 Solution for this problem :

first you can try this steps:

1. when you got " This connection is Untrusted " message, click I Understand the Risks

2. and then click add exception button

3. and then you will see new windows and then click get Certificate

4. after few second click Confirm Security Exception and then the page will loading normally and you now can login to
facebook.

this is simple way to solve this problem and not permanent, because when you login again we must repeat from step 1 to step


5.I tried to find the reason why " This connection is Untrusted " message appear, because at other pc in same network is fine
, I can login normally to facebook. finally I find the reason, the problem is time at your computer is not match with your
local time, I guess this reason why always got this connection is Untrusted message when try login to facebook.

This case not only when you login to facebook, but other website that use https like yahoo, blogspot and others website.

try this second way to fix this problem,

- match you computer time with your local time
to do this go to control panel --->then choose date and time, change the time. Sometimes for few case you cannot resetting
time and date and you got message "you don't have privilege level change system time"

if like this, go to start menu ==> run=== >then type gpedit.msc and then follow this steps:

Local Computer Policy | Computer Configuration | Windows Settings | Security
Settings | Local Policies | User Rights Assignment

then click change system time, for default authorization is for power user and Administrators. If blank click add user/grup
and then click advance tab and then find now, choose user administrator or use that you use now.

and then restart you pc and you now can resetting your computer time.