Firefox blocking the site

Hi Phil,

I've got a major problem since I've updated the Firefox browser (version 52.0.1).

I cannot post or do anything and if I want to login the following message comes:

"404 Not Found

The server can not find the requested page:

www.buzzjack.com/forums/index.php?act=Login&CODE=01 (port 443)

Please forward this error screen to www.buzzjack.com's WebMaster. "

Also it says everytime that the connection is insecure:

"Your connection is not secure

The owner of www.buzzjack.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website."

Can you please check what this could be?

I tried to switch off security for the site but it doesn't want to work.

Also anyone else has the same problem with the new Firefox 52.0.1?

Thank you

Ben