Captchas aren't working if I try (whilst logged-out, or non-autoconfirmed) to add an external link
to https://en.wikipedia.org/wiki/User:Sandbox?veaction=edit
(e.g. http://www.theguardian.com/world/2012/jun/14/egypt-parliament-dissolved-supreme-court)
It just continually reloads a new captcha.
Many similar/recent reports listed at https://en.wikipedia.org/wiki/Wikipedia:VisualEditor/Feedback#Captchas_not_accepted.3F