piclenslite vs Firefox 3 XHTML

A website of mine (http://epii.info/anime/) is using the piclenslite script to facilitate image browsing. It stopped working in Firefox, and after some frustration tracking down the problem, it seems this is due to my site being XHTML. When served up with Content-Type: application/xhtml+xml; charset=UTF-8, the script does not work, but when served up as Content-Type: text/html; charset=UTF-8, it does work.