Dear Stefan,
> > % \pause\begin{figure}
> > % \centering
> > % \includegraphics[height=5 cm]{./hexachorde.png}
> > % \end{figure}
Here you include a file called hexachorde.png. Where is it located? In the
same directory as the tex-file? In that case, you would have include it as
\includegraphics[height=5 cm]{../hexachorde.png}
(note the additional dot, .. being an abbreviation of 'one up in the
directory structure'). This is because the inclusion of this graphic is
done by the pdflatex run, which is done inside the out/ subdirectory you
created during the compilation process.
Hope that helps,
Susan