Ancestry.com needs a special image viewer plugin for Firefox. The manner in which that plugin was installed in earlier versions of Firefox won't work in Firefox 3.6+, so whoever created that plugin would need to re-write that plugin to get it to be able to be installed. That said, a Firefox user can still install that plugin '''manually''' using these instructions. <br /> http://ancestry.custhelp.com/cgi-bin/ancestry.cfg/php/enduser/sab_answer.php?p_faqid=3809&p_sid=lxn4zZWj <br /> Forget the first two paragraphs, use the info under: <br /> '''How to install the Enhanced Imager Viewer manually in Firefox 3.X''' That DLL you need is in this Zip file. <br /> http://c.ancestry.com/Affiliate/Knowledgebase/Images/Ancestry/npImgCtl.zip