Lilypond-book not working after installing Python 3

[Sven Siegmund]

Hello,

I work on Microsoft Windows 7 (64 bit), have MiKTeX 2.8 and lilypond
2.12.3 installed and lilypond-book worked fine until I installed
Python 3.1.1.

Not knowing that Lilypond provides python 2.4.5 I was surprised that
after I installed Python 3.1.1 and ran python, an older version of
Python started. Then I realized it's python 2.4.5 from the
\LilyPond\usr\bin directory. So I modified the PATH environment and
moved the Python 3 path before the LilyPond\usr\bin path. Then the
"python" command launched Python 3.1.1. So the minor python-launching
problem looked like solved, but ...

Lilypond-book does not work anymore. Even when I move the Python 3
path further back again or even when I remove it from PATH completely,
I cannot run lilypond-book because it complains about the syntax line
1037 of lilypond-book.py. Error messages follow, but first here are my
files and folders explained:

The minimal document tutorial.tex which I am trying to compile:
\documentclass[a4paper]{article}
\begin{document}
Text before lilypond
\begin{lilypond}
{
  c' e' g' e'
}
\end{lilypond}
Text after lilypond
\end{document}

tutorial.tex is located in  F:\sven\latex\lilypond,
lilypond-book.py and python.exe (2.4.5) are in c:\Program Files
(x86)\LilyPond\usr\bin
Python 3 is removed from path. Here the commands I tried, first lines
showing that "python" launches the same old 2.4.5 version used by
lilypond-book:

------------
Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
F:\sven\latex\lilypond>python
Python 2.4.5 (#1, Dec 15 2009, 16:41:19)
[GCC 4.1.1] on mingw32
Type "help", "copyright", "credits" or "license" for more information.
>>> ^Z
F:\sven\latex\lilypond>lilypond-book --output=out --pdf tutorial.tex
  File "C:\Program Files (x86)\LilyPond\usr\bin\lilypond-book.py", line 1037
    return `self.__class__` + ' type = ' + self.type
           ^
SyntaxError: invalid syntax
------------

I also tried to run lilypond-book right from the directory where the
old python version and lilypond-book.py are. The results look better,
but still aren't good enough. This is what happens:

------------
c:\Program Files (x86)\LilyPond\usr\bin>python lilypond-book.py --output=f:\sven
\latex\lilypond\out --pdf f:\sven\latex\lilypond\tutorial.tex
lilypond-book.py (GNU LilyPond) 2.12.3
Reading f:\sven\latex\lilypond\tutorial.tex...
Running latex...This is pdfTeX, Version 3.1415926-1.40.10 (MiKTeX 2.8)
entering extended mode
(c:/users/tejul/appdata/local/temp/tmpvpvfe1.tex
LaTeX2e <2009/09/24>
Babel <v3.8l> and hyphenation patterns for english, dumylang, nohyphenation, ge
rman, ngerman, german-x-2009-06-19, ngerman-x-2009-06-19, french, loaded.

("C:\Program Files (x86)\MiKTeX 2.8\tex\latex\base\article.cls"
Document Class: article 2007/10/19 v1.4h Standard LaTeX document class
("C:\Program Files (x86)\MiKTeX 2.8\tex\latex\base\size10.clo"))
No file tmpvpvfe1.aux.
textwidth=345.0pt
columnsep=10.0pt
(f:\sven\latex\lilypond\out\tmpvpvfe1.aux) )
No pages of output.
Transcript written on tmpvpvfe1.log.
Dissecting...
Writing snippets...
Processing...
Running lilypond...GNU LilyPond 2.12.3
programming error: file name not normalized: f:\\sven\\latex\\lilypond\\out\\sni
ppet-names-2093046988.ly
continuing, cross fingers
Processing `snippet-map-2093046988.ly'
Analyzuji...
snippet-map-2093046988.ly:4:1: error: GUILE signaled an error for the expression
 beginning here
#
 (ly:add-file-name-alist '(("a5/lily-cf0998d3.ly" . "f:\sven\latex\lilypond\tuto
rial.tex")
snippet-map-2093046988.ly:4:57: illegal character in escape sequence: #\s
snippet-map-2093046988.ly:4:4: error: syntax error, unexpected ':', expecting '=
'
#(ly
    :add-file-name-alist '(("a5/lily-cf0998d3.ly" . "f:\sven\latex\lilypond\tuto
rial.tex")
Processing `a5/lily-cf0998d3.ly'
Analyzuji...
Interpreting music...
Preprocessing graphical objects...
Calculating line breaks...
Drawing systems...
Layout output to `a5/lily-cf0998d3-1.eps'...
Converting to `a5/lily-cf0998d3-1.pdf'...
Layout output to `a5/lily-cf0998d3.eps'...
Converting to `a5/lily-cf0998d3.pdf'...
Writing a5/lily-cf0998d3-systems.texi...
Writing a5/lily-cf0998d3-systems.tex...
Writing a5/lily-cf0998d3-systems.count...
error: failed files: "snippet-map-2093046988.ly"
command failed: lilypond --formats=ps -dbackend=eps  -I  "c:\\Program Files (x86
)\\LilyPond\\usr\\bin" --formats=eps --pdf -dinclude-eps-fonts -dgs-load-fonts
-deps-box-padding=3.000000  -dread-file-list -dno-strip-output-dir  "f:\\sven\\l
atex\\lilypond\\out\\snippet-names-2093046988.ly"
Child returned 1
------------

Now, can anybody explain me what is going on? Why can't I run
lilypond-book from anywhere and why it does not work even when run
from its own directory?

Looking forward for your answers,

S.