check your line and mic in ( mute em), laptop mostly have noisy soundcards and in case of the mac laptop, there's a this issue with firewire and the psu interferening ( which also means... keep your powercords away from the audiocables! )
I';m so stupid, i never even thought about the audio properties,,,,word. Yeah mute them, that should do the trick yo. I gotta stop smokin,,,,shit is fuckin up my memory,,,