OMG i found out something new!!!
1-uninstalled Avast 6.0.1203 and used Avast AV Removal tool.
2-Installed Avast Free 6.0.1279
Results: NOTHING CHANGED! same problem "system won't shutdown or restart"
BUT!!!
when i use "FireFox 6.0.1" or "IE 8" i face that problem!
when i use "Firefox 6.0.1" or "IE 8" while Avast "not installed in my system
" everything is fine!
forced the system to shutdown using the magical power of my finger
and when windows started again i tried to shutdown it without surfing the internet or using FireFox or any browser and everything went fine!!!
WHILE after writing this post and closing FireFox i'm sure windows not gonna shutdown!
I'M CONFUSED.........