Had a PM on the other site from Ash or Ash saying he couldn't log in again. I just tried logging out (which I don't normally do) and logging back in again and confirmed that you do need to log in 5 times. On the 5th attempt the Captcha box pops up and it lets you in. Hopefully, if people see this when not logged in, it'll tell them what they need to do in the meantime until it's sorted out.

Yup, if you hit refresh five times it shows the captcha. I've filed a bug with the folks who write the forum software and I'm poking at it myself a bit.

How weirdly specific, refresh it five times?

This morning I ran CCleaner to swipe the broom through the system, obviously I had to log in again on all password sensitive apps including the pub.
Filled in username, password atomatically showed in dots, log in. Did not succeed, filled in password manually and got the captcha notification, so on second attempt, and logged in.

Sounds like there's a setting requiring Captcha and another setting to say how many log in attempts are required before Captcha fires up.
Or it's just b0rken :)