I can't compile my beamer file when I insert any equation in it! [duplicate]

I'm having some troubles with my beamer presentation. When I insert any equation that involves letters (either greek or latin), My compilation fails. It doesn't matter whether I'm doing this in equation environment or between . I just don't what's happening, 'cause it should work normally. Here follows my simplified code:

\documentclass{beamer}
%
\usepackage[latin1]{inputenc}
\usepackage[brazil]{babel}
\usepackage{amsmath,array,amssymb}
\usepackage{graphicx,color}
\usepackage{bm}

\usetheme{Warsaw}

\definecolor{orange}{rgb}{1.0,0.647,0.0}
\definecolor{darkorange}{rgb}{1.0,0.546,0.0}
\definecolor{sienna}{rgb}{0.627,0.321,0.176}
\definecolor{navy}{rgb}{0.0,0.0,0.50}
\definecolor{darkred}{rgb}{0.9,0,0}

\title[Blabla]{\mbox{}\\ \vspace{0.1cm} Blabla \vspace{0.5cm} }
\date{\color{navy} Blabla}
\author[bla, \\ bla]{{ \footnotesize \underline{blabla}, blabla} }
\institute{blabla}
\subject{????}

\begin{document}

\begin{frame}
\frametitle{A abordagem perturbativa}
\framesubtitle{}

Partindo da métrica na forma

$$ds^{2} = -h(r) dt^{2} + h(r)^{-1} dr^{2}+r^{2}(d\theta^{2}+\sin^{2}\theta d\phi^{2})$$
\end{frame}
\end{document}


The error message displayed at the end of the process was:

Running miktex-makemf.exe... miktex-makemf: The mathkerncmssi source file could not be found.

Running ttf2pk.exe... miktex-makepk: PK font mathkerncmssi10 could not be created.

LaTeX Font Warning: Size substitutions with differences (Font)
up to 1.0pt have occurred.

) (see the transcript file for additional information) !pdfTeX error: pdflatex.exe (file mathkerncmssi10): Font mathkerncmssi10 at 657 not found ==> Fatal error occurred, no output PDF file produced!

Thanks for supporting!

• Welcome to TeX.SX! I get no error from your file. – egreg Sep 12 '15 at 22:42
• Thank you very much @egreg! So, can the error reside on the installation of my beamer? or in some other package? I've installed my packages through the "install while compiling" mechanism.... – Herr Schrödinger Sep 12 '15 at 22:53
• Please, add the error message to the question, rather than in comments. – egreg Sep 12 '15 at 22:58
• Does tex.stackexchange.com/questions/250413/… help? Look at Ulrike Fischer's comment, rather than the answers. – egreg Sep 12 '15 at 23:00
• – egreg Sep 12 '15 at 23:02