Somewhere there is a line about firefox that said that you had to check or un-check something in the TOOLS area.
I'm not familiar with firefox, but perhaps Echos will know.
There are some sites that IE won't work for me and some that Firefox won't work.
I switch back and forth between browsers.
The problem is with my browsers, but since between the 2 of them I can visit all sites I don't bother trying to fix it.
Try Opera or IE and see what happens.