Disappearing Form Elements

First of all, the demo of the project is awesome. Great work!

On a fresh install, when I go to the form-builder-example page, and when I try to drag any form elements, they will disappear. the field element basically turns into a white block of nothing. I cannot drag it again and the content is gone. You can still configure the elements and add new elements, but once you try to drag them, they will disappear. However, when I get the export code, the fields are shown and the weight is represented correctly, as well. Also, on a disappearing fieldset, I dragged another field inside of it, and it was correctly represented in the export code there as well.

So it just seems like the something with the javascript is causing the element block to just lose all of it's content.

Set-up:
Drupal 6-6
PHP 5.2.1
MySQL 5.0.37
jQuery Update (Module) 6.x-1.1
jQuery UI (Module) 6.x-1.2
jQuery UI (ui.jquery.com) 1.6rc2 && 1.5.3 (both experienced the same problems).