[XeTeX] Issue with xgreek

[heliotropion]

Greetings, list.
I have a small (more annoying than destructive) problem with the
latest xgreek in the MiKTeX 2.8. Every time I try to typeset (through
TeXworks) a file, I get:

("C:\Program Files\MiKTeX 2.8\tex\xelatex\xgreek\xgreek.sty"
Package `xgreek' version 2.1 by Apostolos Syropoulos
! Undefined control sequence.
\ds at monogreek ->\language \l at monogreek

l.436 \ExecuteOptions{monogreek}

? <ENTER>

! Missing number, treated as zero.
<to be read again>
                   \def
l.436 \ExecuteOptions{monogreek}

? <ENTER> )

At those two points, I just press enter and everything results OK.
This happens even with the simplest files, e.g.:

\documentclass[a4paper,12pt]{article}
\usepackage{fontspec}
 \usepackage{xgreek}
\setmainfont{GentiumAlt}
\begin{document}
<greek text>\ldots{}
\end{document}

Any ideas on causes or remedies?
Thanks.
-- 
The jewel that never leaves the mine is never polished. -- Saadi