Update - Check out the all new Custom Sidebar Pro for all your widget, sidebar and footer needs.
Finally a mayor release, Custom Sidebars 1.0 is out! It has a lot of improvements, specially AJAX management. But AJAX relies on javascript, and becouse of that only WP3.3 installations could run the new version of Custom Sidebars.
So if your Wordpress is older than 3.3 DO NOT UPGRADE YOUR PLUGIN.
If you already did, just downloading the version 0.8.2 everything should return to normal.I really would like to explain all the improvements slowly, so I will take my time to update this post, until then, feel free to leave a message.