[OS X TeX] wierd rule behavior

[Joel Anderson]

Dear TeX Experts,

Just recently (less than a week ago) I started to have problems  
printing horizontal lines in tex files.
I prepared a quiz for my math class with a line for the student's name  
and also containing
some square roots.  The line for the name didn't appear on the pdf  
file on the screen, but the horizontal
bars on top of the square roots did.  When I printed the pdf file, the  
line for the name didn't
appear and one of the square roots was missing the line on top.   The  
other 2 square roots
printed fine.

I made a test file as follows.


\documentclass[12pt]{article}

\usepackage{amsmath,amsthm,amsfonts,latexsym,amscd}


\pagestyle{empty}
\begin{document}

\vrule height.1pt width 2in


$\sqrt{2}$

$\frac{\sqrt{2}}{2}$

\[
\sqrt{2}  \quad \frac{\sqrt{2}}{2}
\]

\end{document}

This prints all square roots and the \vrule line fine.  If I comment  
out the displayed square roots at the end,
the \vrule prints, but the tops of all square roots disappear.

I am running TeXShop 2.18-svn with Mac OS X version 10.5.5 on a Power  
Mac G5. I notice that Richard Koch
has announced that a new version of I-installer is available.  But He  
didn't provide a link to where I could
find it.  I wonder why?


Joel Anderson