Weird audio problem with Vaio notebook

I have a friend that has a Sony Vaio VGN SF980 notebook that has a audio problem that has stumped me. From what she describes it sounds like static and as she describes “crunching”. What is baffling about this is that she says that if she uses the recovery disc the noise will go away for about a month and then return. I’ve look at the Sony site for update for the audio drivers, googled for audio problems associated with this model and have found nothing. I can only hope that someone here can help me shed some light on this.

Any help will be greatly appreciated not only by me but by a freshman college student who depends on this computer.

Strange. U may try to ‘mute’ an internal microphone if there is one. Can it be one of the fans, and not audio at all ? Does it do it when powered off PSU or battery or both?
Those recovery CDs are crap BTW