We use current production (not beta / pre-release) releases of x86-64 Linux Mozilla Firefox (as well as Mozilla Thunderbird), not the distro ESR version. There are a number of reasons for this that can be discussed under separate cover. The environment is SL7x. Firefox often (almost always) fails to open, with the diagnostic: [ykarant@localhost ~]$ /usr/lib64/firefox/firefox XPCOMGlueLoad error for file /usr/lib64/firefox/libxul.so: libmozgtk.so: cannot open shared object file: No such file or directory Couldn't load XPCOM. A simple script "fixes" the problem. I keep the run directory /usr/lib64/firefox that has the installed compressed tarball files duplicated in /usr/lib/firefox-current , and then as root superuser rm -rf the run directory followed by a directory copy of the duplicate directory into a new copy of the run directory. Does anyone know what causes current standard production firefox from "destroying" /usr/lib64/firefox/libxul.so ? Yasha Karant