Reference original bug, which I thought was caused by livna's nvidia driver package:

https://bugzilla.livna.org/show_bug.cgi?id=1103

Every time I boot, what I assume is a livna-provided script checks for
availability of the drivers.  Part of this is to run an script which apparently
uses pyxf86config, and for some reason adds stuff like the following to my
xorg.conf file:

 ### Comment all HorizSync and VertSync values to use DDC:

Notice the leading space.  This breaks xorg.conf.  It also adds one or two of
these lines every time the script is run, so that after a couple of weeks of
daily booting, my xorg.conf file is littered with crap.  (I won't even go into
concerns about how it f*s up my hand-formatted xorg.conf file)

Livna has declared that this is not a bug in their
/usr/sbin/nvidia-config-display script, so I am just pushing this bug along to
the next piece of the puzzle.  I *did* check that the string is present in
ixf86configmodule.so.