"Blip" noise

Hey, i have been using XBMC for mac, that works fine.
Now i bought me a PC and use this an HTPC. everything works rather well.

But i get this blip noise out from the soundcard when i start movies and music. i removed any sound in the windows sound scheme and XBMC sounds, but still the same sound comes every time. and it keep doing this when listening to the music or watching the movie.

i have an HP DV5 using quickdock(tried HDMI and other connectors as well)

Update: I used Wireless before and know i use cable, problem solved..... strange