I can't load images with the TinyMCE on the latest version of firefox, do you know why?

I use a wysiwyg editor to edit pages of a website I maintain and ever since the 3.6.9 version got downloaded onto my laptop I can no longer use the insert/edit image feature isn't working. A colleague of mine tested this on 2 pcs and on the 1st pc he has an older version of Firefox and it worked fine. Then he downloaded the new version 3.6.9 and now it doesn't work for him either.