If you boot into runlevel 5 without the 'rhgb' boot option, firstboot
doesn't come up.

> > There also is the possibility of a race condition in firstboot.py when
> > doing a graphical firstboot without rhgb - if xrgb finishes
running before
> > the window manager connects to the X server, the X server may
terminate
> > and ruin the whole thing. Want a bug report filed? I'll try to
stop by and
> > explain what's going on tomorrow.

That's my theory of the cause....