bibunits package gives errors

I'm using bibunits in a number of documents on both Windows (MiKTeX 2.9)
and Ubuntu, and keep getting the same set of errors:

...
(C:\Users\friendly\Dropbox\Documents\grants\form100-13.1.aux)
(C:\Users\friendly\Dropbox\Documents\grants\form100-13.1.bbl

! LaTeX Error: \section *undefined.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
  ...

l.2 \begin{thebibliography}{10}

? r
Pressing r for nonstop mode lets the document compile, but is
annoying.  Does anyone have an idea why this occurs or how to
fix it?

A typical bibunit section in my files looks like this:

% preamble stuff
% bibunit stuff
\usepackage{bibunits}
\bibliographystyle{myunsrt-url1}
\bibliography{vita}
\newcommand{\bibunitstyle}{myunsrt}

\makeatletter
\renewcommand{\@bibunitname}{\jobname.\the\@bibunitauxcnt}
%\newcounter{bibunititem}[@bibunitauxcnt]
\makeatother

  ...

\subsection{Software contributions}\label{sec:software} % .4
  \begin{bibunit}[\bibunitstyle]
	\nocite{candisc}
	\nocite{gellipsoid}
	\nocite{genridge}
	\nocite{Guerry}
	\nocite{heplots}
	\nocite{HistData}
	\nocite{Lahman}
	\nocite{mvinfluence}
	\nocite{p3ddev}
	\nocite{tableplot}
	\nocite{vcdExtra}
	\nocite{WordPools}
\putbib[Rpackages]
\end{bibunit}



-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA


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