dodgy sound - asus eeebox B202???

i have an asus eee box B202, it works fine but recently the sound has been playing up. when the computer is powered on, the windows xp "log on tune" plays, but its VERY distorted, and lags. i then tried playing music, this also lags. and the general windows sounds (pops,blips etc)

i have tryed a different set of speakers, still no luck. i have also reinstalled the drivers, still no luck.

im stumped! if any one could give me a reason to this, and a resolution... that would be great thanks in advance.