Certificate problem, but option to accept anyway has gone.

Question

since upgrading to firefox 16.0 the option to accept a certificate anyway when present with a "This Connection is Untrusted" message by firefox has disappeared. There is now no way I can actually continue to the web site (https) in question. there should be a button to "continue anyway"
this behaviour is on winxp sp3
on linux (slackware 14.0) the site opens fine without any certificate warning or complaints.!
on winXpsp3 with firefox 15.1 site opens fine without certificate warning.
comparing with another browser (ie8) which warns, but gives option to continue

Answer 1

Check the date and time in the clock on your computer: (double) click the clock icon on the Windows Taskbar.
*https://support.mozilla.org/kb/Secure+Connection+Failed
If such a page opens in an (i)frame then you may not be able to add a exception.
You can use the right-click context menu in the browser window to verify that.
It shouldn't be necessary to create an exception for the link that you provided.
You can inspect the certificate chain via a site like this:
*http://www.networking4all.com/en/support/tools/site+check/
Try to rename the cert8.db file in the Firefox profile folder to cert8.db.old or delete the cert8.db file to remove intermediate certificates that Firefox has stored.
If that helped to solve the problem then you can remove the renamed cert8.db.old file.<br />
Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previous intermediate certificates.<br />
Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.<br />