Can't Shutdown PC, only black screen after clicking shutdown

[remehmood]

Hi all, I have installed RC desktop on my pc but i can't shutdown or restart my pc. I can hear sound when clicking shutdown and after that it shows black screen like shutting down. But it never shut down and remain hung in that state. Any answer regarding this is welcomed. My pc specs are
Acer Travelmate 4530
AMD Turion X2 64-bit
2GB Ram
ATI Radeon 3200 HD
Sound Wireless Ethernet is working fine
Nothing wrong with installation too
its 64-bit OS