No "Shut Down..." option in "System" menu

[Merciadri Luca <Luca.Merciadri@student.ulg.ac.be>]

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Hello,

I have no "shut down..." option in my "System" menu (I am using GNOME
front-end). I am thus obliged to shut down using the terminal. How can
I make these buttons appearing?

Thanks.
- -- 
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
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