[OS X TeX] missing symbols in mathptmx with pdftex

[Nathan Sanders]

I posted this query to comp.text.tex, but I thought I would try here,  
since it seems like it may be a Mac-specific issue (the problem arises  
for both me and my friend, who are using Gerben Wierda's TeXLive  
distribution, with TeXShop as the front end):

==========
A friend of mine discovered that some math symbols do not show up in  
Adobe Acrobat (v5.0, if it matters) for a PDF created by pdftex using  
mathptmx.  The following minimal example illustrates the problem:


\documentclass{article}
\usepackage{mathptmx}
\begin{document}

\[
      \sum_{k=1}^{\infty}\frac{1}{k^2}
\]

\end{document}


If this is run through pdftex and viewed in Acrobat, the summation  
symbol is missing.  However, if dvips is used instead, or if the  
pdftex PDF is viewed in another viewer (Preview, Skim, etc.),  
everything is just fine.

Is this a known issue with a known fix?  Preferably something simple  
(my friend is not very TeX-handy) that allows him to use mathptmx,  
pdftex, and Acrobat (to suit his various needs/wants)?
==========

Can anyone else replicate this?  This only response I got on c.t.t was  
from someone who couldn't replicate it with tetex.

Any help would be greatly appreciated!

Nathan

--
Nathan Sanders
Linguistics Program
Williams College
http://wso.williams.edu/~nsanders/