[Tex/LaTex] Beamer Title Inside Node — Line Break

Question

I am creating my own beamer theme, and the way I have conceived the title page needs the title to be inside a tikzpicture node, in this form:

    \node [anchor=center] (title) at ($(box)+(0,.25)$) {%
    \color{white}
        {\usebeamerfont{title}\inserttitle}
        };

It works perfectly until I need to insert long titles and need to break the lines…

If I do:

\title[academic background \& research experience]
  {Academic background \& \\ Research experience}

I get the error:

 ! LaTeX Error: Something's wrong--perhaps a missing \item.

And if I do:

\usepackage{pbox}
\title[academic background \& research experience]
  {\pbox{20cm}{Academic background \& \\ Research experience}}

I get the warning:

 Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
 (hyperref) removing `\pbox '

Does anybody know what is happening here?

EDIT: Please find a MWE below (I have the relevant lines in a .sty file, but adding them inside \mode<presentation>{} works as well)

\documentclass[ignorenonframetext]{beamer}


\mode<presentation> {
    \usetheme{Berkeley}
    \usecolortheme{albatross}

    %PACKAGES, LIBRARIES AND ENVIRONMENTS HERE 
    \usepackage{tikz}
    \usetikzlibrary{calc} 

    \title[academic background \& research experience]{Academic background \& Research experience}

    \author{Name Surname}
    \date[\today]{\today}

    \setbeamertemplate{title page}{

    \begin{tikzpicture}[remember picture,overlay, every node/.style={inner sep=0,outer sep=0}]
        \node [rectangle, fill=gray, anchor=north east, minimum width=.86\paperwidth, minimum height=3cm] (box) at (current page.north east){};


        \node [anchor=center] (title) at ($(box)+(0,.25)$) {%
        \color{white}
            {\usebeamerfont{title}\inserttitle}
            };

            \ifx\insertauthor\@empty
        \else
        \node [anchor=west] (author) at ($(title.south west)-(0,.5)$) {%
        \color{white}
            {\usebeamerfont{author}\insertauthor}
            };
            \fi

            \ifx\insertdate\@empty
        \else
        \node [anchor=west] (date) at ($(title.south west)-(-.2,2)$) {%
        \color{blue}
            {\usebeamerfont{date}\insertdate}
            };
            \fi
    \end{tikzpicture}
    }
}


\begin{document}


\begin{frame}[plain]
%\frametitle{SCB Departmental WIP - July 2013}
\titlepage % Print the title page as the first slide
\end{frame}


\end{document}

Answer 1

Simply pass the align=<value> key to the title node and/or use text width=<length>, so line breaks are allowed.

Here's a little example completing your snippets to a complete example:

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{calc}

\setbeamertemplate{title page}{%
\begin{tikzpicture}
 \node[text width=\textwidth,fill=cyan,minimum height=2cm] at (current page.center) (box) {};
 \node[anchor=center,align=center,text width=\linewidth,font=\color{white}\usebeamerfont{title}] (title) at ($(box)+(0,.25)$) 
   {\inserttitle};
\end{tikzpicture}%
}

\title[academic background \& research experience]{Academic background \& \\ Research experience}

\begin{document}

\begin{frame}
\maketitle
\end{frame}

\end{document}

Aldo, modifications to the font of the contents of a node are better done using the font key (as in my example) instead of doing them directly in the node contents (as in your code).