Parenthesis problem in Xelatex

The number parenthesis () scuh as (1) (2) etc disappear when compiled on xelatex/polyglossia. Adding space character inside the parenthesis is not a solution in my case. So need your help desperately.

MWE:

\documentclass[10pt,a4paper]{article}
\usepackage[quiet]{polyglossia}
\setmainlanguage{english}
\setotherlanguage{arabic}
\usepackage{geometry}

\geometry{hmargin={0.04in,0.04in}, vmargin={0.04in,0.03in}, paperwidth=81mm, paperheight=105mm}
\newfontfamily\arabicfont[Script=Arabic, Scale=0.8]{Tahoma}

\begin{document}
\centering

\textarabic{نتبينت (9) نتيسن}
% Parenthesis with number in it is ignored.

\begin{Arabic}
نتبينت (9) نتيسن
\end{Arabic}
% Parenthesis with number in it is ignored.

%However following works:

\begin{Arabic}
نتبينت ( 9 ) نتيسن
\end{Arabic}

\end{document}

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I have no problem with current TeXLive –  Herbert Jun 9 '12 at 7:12

As a work-around (until the new version has rolled out) one can separate the problematic glyphs e.g. with (\mbox{9}). –  Ulrike Fischer Jun 9 '12 at 11:31