TeX includepdf works differently on Mac vs Linux [closed]

I'm developing on a Mac for a Linux-hosted web app that generates PDF files with TeX. The feature overlays dynamic text data on top of static PDF backgrounds (scanned copies of paper forms).

Everything works fine on the Linux box using pdflatex: the PDF includes appear as backgrounds, with the text data appearing on top. On the Mac however (using MacTeX), the text either doesn't show (apparently covered by the PDF includes) or the PDF includes and text are printed on different pages.

Here's an abbreviated example of the TeX file (full headers included):

\documentclass[letter,12pt]{article}
\usepackage[absolute]{textpos}
\usepackage{latexsym,fancyhdr}
\usepackage[pdftex]{graphicx}
\usepackage{pdfpages}
\pdfcompresslevel=9
\usepackage{eso-pic}
\usepackage{color}
\usepackage{type1cm}
\setlength{\TPHorizModule}{1in}
\setlength{\TPVertModule}{\TPHorizModule}
\textblockorigin{0in}{0in}
\setlength{\parindent}{0pt}
\renewcommand{\ttfamily}{ptm}
\definecolor{gray}{cmyk}{0,0,0,0.1}

\begin{document}

\newpage

\begin{textblock}{2.4}[0,1](5.75,0.451){\sf HELLO}\end{textblock}

\includepdf{/path/to/foo.pdf}

\newpage

\textblockcolor{}

\begin{textblock}{1.2}[0,1](4.28,0.53)
\begin{tabular}{p{0.01cm}p{0.01cm}p{0.01cm}p{0.01cm}p{0.01cm}}W & O & R & L & D\end{tabular}
\end{textblock}

\includepdf{/path/to/bar.pdf}

\end{document}


In the above example, page 1 properly shows foo.pdf and "HELLO" on both Linux and Mac, but page 2 shows only bar.pdf on the Mac, while the Linux box properly shows both bar.pdf and "WORLD". If I move the includepdf before the textblock on page 2, the Mac gives me bar.pdf on page 2 and "WORLD" on page 3.

Note that I'm using tables to achieve a monospace effect, as the bar.pdf form background has letter-boxes that are normally filled in by hand. This seems to be unrelated to the bug however, as bypassing the pseudo-monospace effect yields the same result.

Cheers to any TeX gurus out there who can shed some light!

-
Are the sizes of foo.pdf and bar.pdf also exactly letter? –  Werner Aug 31 '11 at 6:18
What viewers have you used? I wondered if it was two different pdf viewers that were used to examine pdf files on the different platforms. –  midtiby Aug 31 '11 at 6:38
Which versions of pdfTeX are you using on both platforms? –  Martin Schröder Aug 31 '11 at 6:49