I did report his on trac, Ticket #14447, but in the mean time I am looking for a way using a plugin to supress this for users without the update_plugins capability.
No luck refreshing or increasing memory.
My guess is the culprit is masking errors, if you turn that off does ithe CAPTCHA work? I think the problem is that the CAPTCHA is inserted in a way that is removed when you hide the errors.
