@chris M. That’s probably unrelated, it still works on my site (http://rushtips.com/sitemap_index.xml).
The 404 error has happened to me a few times. You can try to re-install it.
I had this problem on http://rushtips.com but I fixed it by adding the script manually to the footer.
<script src="/wp-content/plugins/floating-social-bar/js/fsb.js"></script>
Hope it helps!
