Balance package messes up vertical space between lines in second column [closed]

Question

I am writing an article with the ACM Sigplan class and want to balance the two columns on the last page of my text (before the bibliography section, which is on a separate page).

I usually use the balance package and the \balance command on the last page, but in this case it sometimes messes up the vertical space between two lines in the second column, as you can see here:

The balancing itself is correct. Without balancing, the space at this position is correct. There is nothing special at this position in the source code (just text).

Whether the problem happens, depends on a lot of other things, for example the content of previous pages. It is also not always between the same two lines, the position also varies depending on other document content.

Here is the smallest example where I could reproduce the problem (yes it has three pages, but if you remove any of the first two, the problem goes away):

\documentclass{sig-alternate}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{balance}
\begin{document}

\begin{figure*}[t]
\blindtext \blindtext \blindtext \blindtext
\end{figure*}

foo
\clearpage

\blindtext \blindtext

\balance

\section{Heading}

\blindtext \blindtext

\blindtext

\blindtext

\end{document}

In this example, the problem occurs between the 6th and 7th line in the right column of the last page (compiled PDF).

I use pdflatex (version 3.1415926-1.40.10 TeX Live 2009/Debian), and several PDF viewers show the problem (at least evince and acroread).

I also tried the flushend package, with no effect at all, and the \balancecolumns command provided by the document class, which produces completely wrong layout.

I have it working with a manual column break at the right position in the text (using \vfill\pagebreak\noindent), but I'm wondering if there is an automatic solution, of if I can fix the problem with the balance package.

I cannot change the provided class file or use the multicol package instead of \twocolumn.