Problems with google stuff on Firefox

Question

Recently, My Firefox has problems with googling stuff. For example, when I try to access simple Google.com on the address bar, it gives unusual error:
Secure Connection Failed
www.google.ca uses an invalid security certificate. The certificate does not come from a trusted source. (Error code: sec_error_inadequate_key_usage)
The page you are trying to view cannot be shown because the authenticity of the received data could
not be verified.
Please contact the website owners to inform them of this problem. Alternatively, use the command
found in the help menu to report this broken site.
Firefox gives me the same error message when I try to find information by entering the simple entries such "News", "Microsoft" and etc on the address bar. Apparently, I can't use Firefox to google.
Do anyone know what's wrong with my Firefox browser and how can I resolve the issue ?

Answer 1

A few other thoughts:
(1) If you access Google in IE and click the padlock icon in the address bar to view the certificate, what do you find in the "Issued by" section as the issue? I have attached the info from Firefox for comparison; I don't have a modern version of IE on this PC.
(2) Do recall changing any encryption-related settings, either through the Options dialog or using the about:config preferences editor?
You could check for non-default settings as follows:
(A) In a new tab, type or paste '''about:config''' in the address bar and press Enter. Click the button promising to be careful.
(B) In the search box above the list, type or paste '''ssl''' and pause while the list is filtered
If any of the preferences whose names start with network. or security. have been customized, they likely will be bolded and show "user set". Could you post those by right-click copying the preferences and then right-click pasting into a reply?