Here's what they said:
Been trying to join Bookcrossing for a few days but I stumble upon the error message mentioned in the title after I've filled the required fields and tried to validate.
No Captcha has showed up on my screen as far as I know.
Been using IE and Chrome (don't know if it helps).
Anyone knows a way around this? Or what it's all about?
Seems like a way to prevent new people joining in. Maybe the site is left for dead?
EDIT : I contacted the website to bring the issue to their attention a few days ago (last week) but no news from them.