does snow leopard have any problem with Arabic language cause i noticed strange behavior with word the letters are not linked together every letter alone
Right, MS Word for OS X has never yet supported Arabic (or any Indic language either).
in pages its fine but the cursor don't move between letters and when i type it stays at beginning of the line although i can type why is that happening ?
Because, while Pages does support Arabic (and also Indic), it has various bugs which make it unsuitable for RTL scripts for most people (unless copy/paste from elsewhere is enough). Same for Keynote and Numbers and iWeb.
Use instead Mellel, TextEdit, Nisus Writer, OpenOffice, etc.
http://homepage.mac.com/thgewecke/TypingArabic.html