hello, on a https site where the option is available, please attempt to add an exception on the bottom of the error page & inspect the certificate (see the screenshot attached for instructions):

• which issuer information does the certificate contain?

thank you!

You can check the connection settings.

• Tools > Options > Advanced > Network : Connection > Settings
• https://support.mozilla.org/kb/Options+window+-+Advanced+panel

If you do not need to use a proxy to connect to internet then try to select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly.

See "Firefox connection settings":

• https://support.mozilla.org/kb/Firefox+cannot+load+websites+but+other+programs+can

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

@philipp - First thanks for the reply. It doesn't only happen on https site but on all sites even mozilla support and all the ones I normaly go to. In clear it does it to every sites. Then, if the option is sometimes available, I do not want to spend my time adding an exception every frigging time. But thanks..

@cor-el Thank you too for the reply I tried the proxy procedure you mentionned but it does not solve my problem I have already tried various virus scan and malwarebytes. My system is clean

I have a feeling that it must be somehow in conflict with Mcafee, do not know why, but my gutts tell me they both must try to do the same thing and do not know which is which.. hence this stupid block

On my search on the Internet, I have seen someone talking about SSL or Sll conflict, but did not understand what must be done. Any idea ?

@NMH1, you should not add exceptions to all sites! this is only a one time trouble-shooting procedure, try it once with the procedure explained above and report back with the issuer information, since this might provide a clue what is at the root of the problem.

@philipp,

so it says  : Nom commun (CN) VeriSign Class 3 Public Primary Certification Authority - G5 Organisation (O) VeriSign, Inc. Unité d’organisation (OU) VeriSign Trust Network

ok, this looks genuine. does this also happen as well you launch firefox in safe mode like described at Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems?

@Philipp, yes it does. Also when I reset Firefox it erases all add-ons, so add-ons cannot be the problem in this instance. I am presently running a a brand new reinstalled-from-scratch-firefox, with no preferences, no add ons and it still does it. Does not occur on Internet Explorer which I am presently using as Firefox would not let me on this forum even if I add an exception.

this is very strange - does it also happen as well when you try a portable version of firefox on your machine?: http://portableapps.com/apps/internet/firefox_portable

@Philipp, did not try this yet, I will try tomorrow (it is night time here) and will let you know Thanks anyway

@Philipp, just tried the portable version. Same problem ...

can you run the hijackthis tool from http://sourceforge.net/projects/hjt/ and provide a log either in a forum reply (or if it doesn't fit, paste it into http://pastebin.mozilla.org/and provide a link to that)?

"For some reason your system denied write access to the Hosts file. If any hijaced domains are in this file, HijactThis may NOT be able to fix this. If that happens, you need to edit the file yourself..." then it tells me how to do it and to delete the lines HijackThis reports ... but there are not any ....

this notice is appearing when you don't run the toll with admin rights. please try to right-click it and select "run as administrator" to get the full log...

Right, but when I closed the pop-up window, it all came up, but would not let me paste it here, so there it is :

http://pastebin.mozilla.org/6389415

on first sight this looks all fairly common. this is starting to remind me of a problem we had a little while back which turned out to be something isp related: https://support.mozilla.org/en-US/questions/976504

one test you could still run is to see if the issue is occurring when you boot windows in safe mode with networking enabled: http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7

Hi Philipp, I do not think it is isp related since, but correct me if I am wrong, it would do it to when I reset Firefox. I have one more time uninstall and erase firefox from the registry I will reinstall and see what is happening. I'll keep you posted

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. Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previous intermediate certificates. Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.

If that didn't help then remove or rename secmod.db (secmod.db.old) as well.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

Hi cor-el, I tried before deleting cert8.db to no avail, however did not try renaming it. I will try this, once I have reinstall firefox should I have the same problem. Will do this tomorrow though, (it's night time here)

I found this : http://kbeezie.com/untrusted-connection-firefox/ Is this safe to do? and if so, could it fix the problem? If so, where do I find my certificate (should I have one even if I do not have my own domain)