Of course there were headbutts! Basically, X failed to launch: The Fedora progress screen just hanged after it appeared everything was done. According to the detailed boot log (type escape during the Fedora boot), the last daemon to launch was Avahi, but it launched [ok]. There was no message that X was trying to start, which I think is a bug. Since I suspected a graphics-card driver/settings problem, I changed the runlevel from 5 to 3 in /etc/inittab and then I could boot up to a login prompt with no problems. Oddly, my USB disk drive did not mount correctly into /media/name at runlevel 3, and I thought for a good while that it had been wiped out during the upgrade by some bug. (After all, the preupgrade instructions only say disks will ``not necessarily'' be wiped out during the install. ) Fortunately, however, the automount works great at runlevel 5 (GUI mode), and the files are all there after all.
I had at least two problems that I know about so far:
I figured out problem (1) by searching for ``Fedora 13 radeon hang'' or the like, because I suspected my oft-recalcitrant graphics card, and hit upon the ``basic test'' for the radeon driver for Fedora 13 testing. One of the instructions was to make sure xorg.conf did not exist!
Regarding my home-directory problem (2), when I tried startx as me, xauth tried to create an infinite number of authority files until there were no more processes and the world locked up. I tried deleting all .X* and .x* files in my home directory, but that didn't help. It finally worked to move my home directory to a new name, copy in a newly created home directory (see man useradd), and edit all occurrences of the username to my name (and ownerships, etc.), and delete all cookie-looking files--this was not too tedious, because the initial user files are admirably small, but it would have been easier to change my main username (but of course I refuse to do that--it is not good to let the computer win, ever). I would submit, by the way, that files created for a new user should all contain $HOME instead of the actual username (most do already).
After finally getting logged in as myself under X, I got an SELinux alert that my home directory was not the right type. This is surprising because I copied it using cp -rp, where `p' means ``preserve,'' but evidently not all properties were preserved. I was able to fix that in nautilus (an editable property). I suppose this could explain the xauth problem, but the error alert said access was NOT denied due to being in ``permissive'' mode. So, that lossage is still a mystery, as are the fatal aspects of my old xorg.conf file.
My HP LaserJet did not work right away, and the error message was that ``There is a missing print filter''.
F13 is looking really good now, but I have some work to do to carefully move in my prior state. Fortunately, most of my prior state is a set of links to personal data on a different disk, precisely to make fresh installs go faster.