John: If I'm guessing correctly at what you are referring to, that lock represents whether a web site is secure or not and the line MIGHT indicate that you are accessing an unsecure site. That's not necessarily a bad thing. A site like routerforums isn't running a secure connection - there would be no reason to. On the other hand, if you access your bank login through the web, you would definitely want a secure connection and would see a lock.
It may depend as well on what browser you were using and whether or not it recognized an updated security certificate.
Again, it depends a lot on your end and if you could take a screen shot of the icon, might be able to give you more detailed advice.
I don't see any security lock when I access the forum with any browser, and in fact if I click on the info button next to the URL line, it specifically says the "connection is not secure".
Lastly, does it prevent you from accessing any thread?
Some folks call me Vince - other folks call me...........