On my machine /usr/lib/iceweasel/firefox-bin is a link to /usr/lib/iceweasel/iceweasel . So maybe on your machine /usr/local/share/firefox-3.6.28/firefox-bin is a dangling link. What is the output of $ ls -lF /usr/local/share/firefox-3.6.28/firefox-bin Regards, jvp.