Your lightbox code in conjunction with Image Handler seem to not be escaping ' marks properly.

document.write('<a href="javascriptopupWindow(\'http://test.possumbooks.com/index.php?main_page=popup_image_additional&amp;pID=232&amp;pic=0&amp;products_im age_large_additional=images/Illustrated Fairytales_01.jpg\')"><img src="bmz_cache/e/ef2387c104eb5dbe00217b48e5e57cd2.image.100x63.jpg" alt="Illustrated Fairy Tales" title=" Illustrated Fairy Tales " width="100" height="63" style="position:relative" onmouseover="showtrail('bmz_cache/d/d75abaa72c100a305044756fcc6d7193.image.180x113.jpg','Illustrated Fairy Tales',100,63,180,113,this,0,0,100,63);" onmouseout="hidetrail();" /><br />larger image</a>');

The whole document.write line is inside single quotes, which means any use of single-quotes in the rest of the document.write command must be escaped.

ie: good escaping:
Code:
javascript:popupWindow(\'http://test.possumbo
ie: bad escaping:
Code:
onmouseover="showtrail('bmz_cache/d/d75abaa72c100a305044756fcc6d7193.image.180x113.jpg','Illustrated Fairy Tales',
One or both of those mods isn't doing everything correctly.