I just stepped through from login to this thread.
The ssl connection is secure all the way in until this thread loads, and its from the non ssl urls in that list.
So a browser should only throw this message once the OP enters any thread with any of the non-ssl images listed above.
N3V needs to change those image urls to use the ssl url, when the client is using ssl.
But that will not solve any linked images and such.
The true answer is to ignore it, or turn off the notification for this site (forums.auran.com), because even if N3V fixes the urls, peoples signatures and postimages will make the message come back.
The entire WEB is switching to SECURE, and this is the result, sites not having secure ability.
The only time this is an issue to be concerned with is if you are purchasing something and the web store you purchase from causes your browser to show that message, this might indicate your transaction is being recorded.
If I ever tried to purchase something at a site that said this, i would stop, and purchase on the phone, in person, or contact the company.
Even when SOME connections your computers browser makes are insecure, that doesn't mean the secure connections are compromised.
Browsers connect to hundreds of sites at once using multi-threaded connections, and some, are bound to be insecure.
When you have insecure connections the risk is that a middle man attack could be possible. So unlikely tho, many conditions must be met for that.
Just don't buy things on a web-store which has that message, on a wireless connection in a coffee shop that has no password for the wireless, and your ok. (you know how many people do that? its crazy)
If I wanted to be a criminal, id data mine local coffee shops. (but even then most browsers and webstores encrypt the socket that is transferring the payment info, so it would be pretty futile, i might enjoy some coffee, but not much else)