rel-0-8-1; \PreviewEnvironment{tabular} recognizes tabularx, but displays it wrong

Remember to cover the basics.  Including a minimal LaTeX example
file exhibiting the problem might help.

In the following minimal example, the tabularx environment is
displayed as a preview, seemingly because it is matched by a search
for tabular environments. However, the display is wrong: The picture
is positioned after \end{tabularx}, and the source text is still
visible. With the commented line activated, it is o.k., but it would
be better if either tabularx would be correctly displayed, or not at
all. 

Similarly, if both \PreviewEnvironment lines are commented out, then
the math in the tabularx line is also displayed at the wrong place:
Again after \end{tabularx}, and the source code is still there.

\documentclass{book}

\usepackage{tabularx}

\usepackage[footnotes,graphics,floats,textmath,displaymath]{preview}
\PreviewEnvironment[{[]{}}]{tabular}
% \PreviewEnvironment[{[]{}{}}]{tabularx}

\begin{document}

\begin{tabularx}{0.7\linewidth}{lX}
DMSO-Peak      & Im Abfall ein Peak mit $\lambda_\mathrm{max}=280 \mathrm{nm}$             \\
\end{tabularx}