K2 2.5.7 with Joomla 2.5.6

I'm having an issue with users registering on our site and can't pin down the problem.
The error I'm getting in firebug is:
window.onDomReady is not a function
www.++++++++.com/component/users/?view=registration
Line 315

What happens is that when I test the form and press submit, I get returned to the same empty from and nothing has happened.

I have tried disabling the Joomla reCapture, enabling it, putting in the same details and many other configurations but to no avail.!

FYI:

FIxed - I disabled the reCaptcha in the main configuration but didn't realise it needed disabling in the user configuration too, once done it worked.

Hi. You mean that you also has to disable the Joomla! core reCAPCTHA implementation? We are going to take a look on this. Thanks for your feedback.