d13slideshow.php calls the scriptaculous effects through:
This causes 404 errors because, somehow, the effects are all loaded with an incorrect prefix (wp-builder.js instead of builder.js, etc).
(line 606) ...wp-includes/js/scriptaculous/scriptaculous.js
(line 606) ...wp-includes/js/scriptaculous/wp-scriptaculous.js
the error is resolved.
I recommend making this a change in a release soon, as it was generating literally thousands of 404 errors on my site.