Was just a thought, it would obviously need some thinking.
Anyway, there's a potential bug, or rather.. an oversight.
If I click on the login button located in the top left corner it takes me to:
https://bitcointalk.org/index.php?action=login This is fine (obviously) and the login form there displays the captcha.
If you take any action and you're not logged in (for whatever reason) it shows up as this, with no captcha loading:
https://s23.postimg.org/qh9hk7w9n/captcha.pngExample: having a bookmark with
https://bitcointalk.org/index.php?action= (any action, example: pm reply, thread reply, etc) or using a custom PM notification app and needing to quickly reply or so forth.
It correctly tells me to login but it doesn't display the captcha there, hence I can't login using that form, I have to click again on the top left button so it takes me to the original login form, located at
https://bitcointalk.org/index.php?action=login I'm not using an addblocker or noscript, tried it in multiple browsers, captcha doesn't load in any of them. So I'm guessing it's on your end.
Steps to reproduce:
Make sure you're not logged in.
Have a bookmark in your browser with a link entailing an action, let's use this for example:
https://bitcointalk.org/index.php?action=pmClick the bookmark
Done.