Problem with hyperref in beamer

Question

I want to make a presentation using beamer and I have the following problem with the hyperref package. I have already seen that this package causes many troubles for many people. Anyway... Here is the code:

\documentclass[]{beamer}
\usetheme{Warsaw}
%\usepackage{Definitions}
\usepackage[english,greek]{babel}
\usepackage[utf8]{inputenc}
\usepackage{kerkis}
%\usepackage[unicode, bookmarks = true]{hyperref}

\begin{document}

\begin{frame}
\frametitle{\textlatin{Contents}}
\tableofcontents
\end{frame}

\section{\textlatin{Section 1}}
\begin{frame}
\frametitle{\textlatin{frame 1}}
\textlatin{First frame of section 1}.
\end{frame}

\section{Τμήμα 2}
\subsection{Υποτμήμα 1}
\begin{frame}
\frametitle{\textlatin{frame 3}}
\end{frame}

\end{document}

I get these errors and warnings:

"Option clash for package hyperref" and "Glyph not defined in PD1 encoding".

How am I to avoid these errors and warnings? The consequence is clearly seen in the following image, where the most greek letters are missing on the bookmarks (left) side.