If you are sporting a new template or have made some changes to your website code and you suddenly get a non-displaying Captcha (but label shows), and/or the dreaded jQuery(‘hasToolTip’)… error; these are actually interrelated issues.
The problem is that you are likely missing the correct jQueryUI library, from which the Tooltip library springs.
Download the latest: http://jqueryui.com/download/
FTP/upload the file to your template /js and add the following code to your index.php file, after the jQuery main library call:
Change your path and clear the cache, try Ctrl + F5 to refresh the page where your captcha is supposed to be running, voila!
Hope that helps someone :) Merry Christmas