I had exactly the same problem like jackboberg. I was using dynamic form loading into jquery dialogs then attaching various widgets (datepickers, ckeditors etc...). And I tried all solutions noted above, none of them worked for me.
For some reason ckeditor only attached the first time I loaded form, the second time I got exactly the same error message jackboberg did.
I've analyzed my code and discovered that if you attach ckeditor in "mid-air" that is while form content is still not placed into dialog, ckeditor won't properly attach its bindings. That is since ckeditor is attached in "mid-air", second time you attach it in "mid-air"... poof ... an error is thrown since the first instance was not properly removed from DOM.
This was my code that ptoduced the error:
var $content = $(r.content); // jQuery can create DOM nodes from html text gotten from <xhr response> - so called "mid-air" DOM creation
$('.rte-field',$content).ckeditor(function(){});
$content.dialog();
This is the fix that worked:
var $content = $(r.content).dialog(); // first create dialog
$('.rte-field',$content).ckeditor(function(){}); // then attach ckeditor widget