When installed, it replaces mozilla with firebird, such that "mozilla" actually launches firebird, and "mozilla -mail" is broken ('cannot locate /content/messenger.xul'). Furthermore, uninstalling firebird does not fix it! Nor does re-installing mozilla.
I've experienced this in 9.1 by untarring the MozillaFirebird.tgz in /usr/local, and in 9.2 by installing the mozilla-firebird rpm from contrib. (And my mozilla-1.4 in both cases came from Mandrake rpms).
A workaround (to run the real 'zilla) is to add the directory containing mozilla-bin to $LD_LIBRARY_PATH (otherwise it complains about libmozjs.so not found) and run mozilla-bin instead of mozilla.
So firebird seems to be replacing chrome or changing environment paths such that you cannot (easily) run the two browsers side-by-side.
-- Guy
