From Mexico.purplecow.org
LaTeX Beamer with verbatim blocks
Overview
Placing a normal \begin{verbatim} \end{verbatim} pair in a Beamer slide breaks with a message along the lines of "Paragraph ended before \@xverbatim was complete."
Fix
Declare the frame fragile first.
\begin{frame}[fragile]
Code
\begin{frame}[fragile] \frametitle{My title} \begin{verbatim} My block of verbatim text ... ... ... \end{verbatim} \begin{itemize} \item First point about slab of verbatim \item Isn't verbatim great? \end{itemize} \end{frame}