Intermittent buzzing sound on Acer Aspire 5750

Hi,

I have had my Acer Aspire 5750 for 11 months and pretty much since day 1 there has been an intermittent buzzing sound occur, on average, every 5 minutes.    I would point out that the buzzing sound only occurs if you playing something that has sound, e.g. a CD, a YouTube clip, a video file.  The majority of the time I am using the laptop for excel, word, web browsing and email and, as none of these things contain sound, the laptop works perfectly well with no issues.  When I play something with sound, I will hear a short buzzing sound lasting approximately 2 seconds and then everything will continue as normal for another 5 minutes, approximately, until the next buzzing sound.  The problem is not any better or worse than when I first got the laptop but I'm at a stage where I would like to play more music on my laptop but currently with this buzzing sound, it is too annoying to do so.  If I am playing a video file then, at the point that the buzzing occurs, the picture will also stutter but then continue as normal once the buzzing sound has stopped.

Is there anyone out there who has experienced the same thing or knows how to get rid of this buzzing sound?

The technical details of my laptop are:

Windows 7 Home Premium (Service Pack 1)

Intel Core i5-2430M 2.4GHz

Intel HD Graphics 3000

64 bit Operating System

If you need me to provide any further details, let me know.

Cheers