in Debian Woody, I noticed when trying to run dpkg-reconfigure xserver-xfree86, that when you already have an /etc/X11/XF86Config-4 file created with xf86config, and try to let debconf take it over, when it tries to create a temp file, it fails saying it cannot find /etc/X11/XF86Config-4-dexconf-tmp, and I think the "dexconf" part is a typo.