(./presentation.out) (/usr/share/texmf-tetex/tex/latex/psnfss/t1ptm.fd)
! Misplaced \crcr.
\endtabular ->\crcr 
                    \egroup \egroup $\egroup 
l.30 \maketitle
               
? 
! Emergency stop.
\endtabular ->\crcr 
                    \egroup \egroup $\egroup 
l.30 \maketitle