Incomplete Shutdown

Hi Guys,

I have just dual booted my system with Latest Kali Linux 64 Bit version (Windows 7 previously installed) and everything is fine except that I am unable to shutdown,reboot Linux completely.When I click on shutdown option everything goes black but the machine is still On, only black screen is shown for hours.Though, today I realized that I am able to completely Shutdown/Reboot from the Login Menu.......pls help me out guys