error with frame border and beamer poster

[r]

Readers,

With the fancybox and beamer poster packages, I tried the following
commands:

\documentclass[final,hyperref={pdfpagelabels=false}]{beamer}
\mode<presentation>
\usepackage[showboxes]{textpos}
\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{amsmath,amsthm, amssymb, latexsym}
\usepackage{fancybox}
\usefonttheme[onlymath]{serif}
\boldmath
\usepackage[orientation=landscape,size=a0,scale=1.4]
{beamerposter}
\setlength{\TPHorizModule}{1mm}
\setlength{\TPVertModule}{1mm}
\title[Fancy Posters]{Making Really Fancy Posters with \LaTeX}
\author[Dreuw \& Deselaers]{Philippe Dreuw and Thomas Deselaers}
\institute[RWTH Aachen University]{Human Language Technology and
Pattern Recognition,RWTH Aachen University}
\begin{document}
\begin{frame}
\ovalbox\begin{textblock}{x}(y,z)
{\normalsize\color{black}
some text
\end{textblock}
\end{frame}
\end{document}

The error shown below occurs. Any help to solve this error please?

! Improper \prevdepth.
\TP@commonendtextblock ...P@prevdepth =\prevdepth
\prevdepth =-1000pt
\expan...

yours,

la...@conference.jabber.org