It looks like Rob's problem was that something reset the path for the firefox button in Gnome back to the default. That and/or a change in default path that is set when the window manager is invoked meant that the button was attempting to invoke the system firefox instead of the wrapper script.
I put a wrapper in /local/bin/firefox that checks the user id and runs the /home/cdaq/bin/Linux/firefox if invoked as cdaq, otherwise it runs the default firefox. '/local/bin/' should be left alone by Redhat and it seems to be auto-added to the path before /usr/bin/ so takes precedence over the system version.
This wrapper is in place for cdaqlX, ccomptl1, ccomptl2.
(/usr/bin/firefox is actually a wrapper itself, so now there is a wrapper for a wrapper for a wrapper...)