The latest update by firefox to 3.6 has caused problems with the trustfax as well as many other well knowns sites. Trustfax is not able to create a work around to the firefox caused problem at this time.
Suggest that you use Internet Explorer or safari . Or you can unistall version 3.6 and install the working version of firefox 3.5.7.
go here to find the 3.5.7 firefox download:http://www.mozilla.com/en-US/firefox/all-older.html