Small bit more data on the installation glitch. First, I discovered I
had the GNUWin32 bin directory (which contains the same version of sh
and a more recent version of sed) ahead of the MinSYS bin directory on
my path. I temporarily removed GNUWin32 from the path and had the same
installation glitch, ruling that out as the culprit.
Also, when the installer concluded by starting LyX (after not running
the configuration script), I tried working a bit with LyX. It has the
correct preferences loaded (from my existing ones in the Application
Data tree), I can load and edit documents, and I can save them, but I
can't view them. All the relevant options are active on the View menu,
but clicking View->DraftDVI coughs up an error message saying that Yap
can't find the DVI file, and clicking View->DVI coughs up an error
message saying the Python script failed. Once I close and restart LyX,
everything works fine.
Paul