Comment 3 for bug 133786

sudo dpkg --purge --force-all firefox
sudo apt-get install firefox

seemed to fix this. (or adding /usr/lib/firefox to /etc/ld.so.conf.d/libc.conf but I did this for a problem staring gxine)

For now, I will close this bug. If the problem persists in a new Gutsy install I will reopen it. I will create a new bug for gxine if I continue to experience any issues with that (missing libmozjs.so).