Hi friendz

I need some help  when i am in cubase and using fireface asio the windows sounds and media player disabled sounds and just cubase the one i can hear sound , when i close cubase sound come back to windows
i need to make all work windows sounds and cubase in same time

and all time the sound is make drop outs, crackling  i take my RME FF800  and try it in another computer core i7 and it work without drop outs, crackling

so what that thing in my computer doing this ???????? or i must change my computer  !!!

4 giga ram ddr2

core 2 quad q6600 2.4GHz

windows 7 32 bit