i can't write in arabic when i change option in control panel..... please help

salam,
my windows xp professional was writnig in arabic. but i don't know what happend. the arabic enable dissapear and when i go to
control panel_regional lang_language_detail_add_arabic.
when i choose any arabic countrey it show

wndows could not properly load arabic.. arabic keyboard layout

what should i do...
please help me

format

the shortest way man ?!!