Question Author
Thanks for your suggestions. I am using Windows 7. I have Norton and and wi-fi not dial up. This sound just appeared "out of nowhere" and I assumed it was linked to one of the windows updates that randomly occur. I think it is possibly linked to the internet connection because it sometimes also happens when I open emails through windows mail but not immediatey just a few seconds later when the emails are ready to read. - Other than that I am completely at a loss. I will however try removing my USB bluetooth device and see if that helps.