Empty span tags inserted

I've been using Image Attach for a while. Today while inserting new content (a story), everything seemed to behave normally, except when I clicked save, the span tag was inserted, but nothing else:

<span class="inline right"></span>

I'm using the "Full HTML" input filter (with "inline images" enabled).

Any ideas?

Drupal 5.2 - File system - Writable (public download method)
MySQL 4.1.21
PHP 4.4.2

Image 5.x-1.5
Image Assist 5.x-1.4
Teaser Images 5.x-1.x-dev