Firefox should work normally with basic security software like the Windows firewall and Windows Defender.

If you re-do the test from this post:

https://support.mozilla.org/questions/1101166#answer-822912

and check the second tab, does the hierarchy look like the attached?

A user in another thread had problems with a GoDaddy cert and his hierarchy showed a mysterious higher certificate. The solution there (https://support.mozilla.org/questions/1099073?page=2#answer-819332) was to delete the GoDaddy cert from Firefox's Certificate Manager, but in order to suggest exactly what to delete, please take a look at your hierarchy first.

Please reinstall your anti-virus and firewall for your protection.

Try to rename the cert8.db file (cert8.db.old) and delete the cert_override.txt file in the Firefox profile folder to remove intermediate certificates and exceptions that Firefox has stored.

If that has 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 previously stored intermediate certificates. Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.

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

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

jscher2000 said

Firefox should work normally with basic security software like the Windows firewall and Windows Defender. If you re-do the test from this post: https://support.mozilla.org/questions/1101166#answer-822912 and check the second tab, does the hierarchy look like the attached? A user in another thread had problems with a GoDaddy cert and his hierarchy showed a mysterious higher certificate. The solution there (https://support.mozilla.org/questions/1099073?page=2#answer-819332) was to delete the GoDaddy cert from Firefox's Certificate Manager, but in order to suggest exactly what to delete, please take a look at your hierarchy first.

Hi Jscher,

Yes, the heirarchy looks the same when I did the test - no higher certificate shown.

I went and deleted the certificate out of the database too (having already done the rename database earlier) This had no effect.

I'm beginning to think its not just a firefox issue. I have tried Chrome and it works but only occasionally which is a bit wierd.

Cheers Helen

FredMcD said

Please reinstall your anti-virus and firewall for your protection.

Don't worry, I did that straight away :)

cor-el said

Try to rename the cert8.db file (cert8.db.old) and delete the cert_override.txt file in the Firefox profile folder to remove intermediate certificates and exceptions that Firefox has stored. If that has 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 previously stored intermediate certificates. Firefox will automatically store intermediate certificates when you visit websites that send such a certificate. You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Hi Cor-el,

Did that a while ago but without success. I also have just tried deleting the individual certificate out of the database.

Cheers Helen

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of the involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

cor-el said

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page. Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note. You can't recover from this 'forget' unless you have a backup of the involved files. If you revisit a 'forgotten' website then data from that website will be saved once again.

Hi Cor-el,

Thank-you for the tip - still no luck though.

Cheers Helen

Just out of interest I downloaded Tor browser and this is able to access the site without issue. Of course, Tor accesses the website anonymously.

Chrome and IE could on occasion access part of the site but now appear to be as restricted as Firefox.

I'm not quite sure what this means, any ideas from anyone?

Thanks Helen

SpoodleDoodle said

Just out of interest I downloaded Tor browser and this is able to access the site without issue. Of course, Tor accesses the website anonymously.

That's a useful test. What Tor does is bypass your internet service provider and instead route your requests through someone else's internet service provider. The difference could be related to DNS resolution or some other settings difference between the providers.

jscher2000 said </blockquote> That's a useful test. What Tor does is bypass your internet service provider and instead route your requests through someone else's internet service provider. The difference could be related to DNS resolution or some other settings difference between the providers. </blockquote>

The thing that's baffling me though is that I have tried it using a different computer on this network, and the other computer worked fine.

Hi All,

Its been some time, but just for completeness, this issue here was with using British Telecom, the ISP. They did something, I don't know what. We have changed ISP and everything is working fine.

Its all a bit of a mystery what BT did but the ISP was the the issue. Thank you for all your help.

Regards Helen