Conflict between flexisym and polynom packages

Question

After isolating the problem, an aberrant behavior shows up if flexisym and polynom packages are added in beamer. The execution process jams indefinitely without any sign of errors. The following minimal working example elucidates the issue.

\documentclass{beamer}
\usepackage{amsmath,polynom}
\usepackage{flexisym}

\begin{document}

\begin{frame}[fragile]
\begin{center}
    \polyset{vars=s}
    \polylongdiv{s^2+1}{s^2-3s+2}
\end{center}
\end{frame}

\end{document} 

Answer 1

The flexisym package changes the category code of ^ and _ to 12, in order to make them math active.

The problem is that polynom uses the characters ^ and _ with their standard category code to do tests.

Best solution

Forget about flexisym

Working solution

Load polynom with the appropriate category code setup.

\documentclass{beamer}
\usepackage{amsmath}
\usepackage{flexisym}

\catcode`^=12 \catcode`_=12
\usepackage{polynom}
\catcode`^=7 \catcode`_=8

\begin{document}

\begin{frame}[fragile]
\begin{center}
    \polyset{vars=s}
    \polylongdiv{s^2+1}{s^2-3s+2}
\end{center}
\end{frame}

\end{document}