I'm curious about this part:

Clicking i understand the risks again takes me to the blank page and refreshing does nothing.

Where is this message appearing (pop-up, in the page, toolbar) and do you see any explanation for it? If you're getting the page saying there's a problem with the site's certificate, could you view the "Technical Details" section and see what it says there?

Also, did this problem just start after an upgrade (for example, the recent update from 25.0 to 25.0.1) after Firefox was working normally before? Or is this problem occuring on your first run of Firefox?

After a second reading, my comprehension improved.

We need a little bit more information about the security certificate. Could you try Google at https://www.google.com/ and trigger the error there. If you already added an exception and can't trigger the error on that site, try a different secure page such as https://jeffersonscher.com/res/jstest.php.

If you expand the third section of the page ("I understand the risks") and start the process of adding an exception by clicking the Add Exception button, then you can click the View button to see the details of the site's certificate.

In particular, who is listed as the issuer? Does it mention your security software provider (e.g., BitDefender or ESET) or some other third party other than Geotrust and Google Internet Authority? (I've attached what I see for Google.)

You can cancel the Add Exception process after viewing the certificate.

hi problem seems to have disappeared after running ccleaner to remove temp files. will reply if problem reoccurs. Thank you for your help...it is much appreciated as self is not so familiar with firefox being a recent migrant from the sinking ship opera.