I got the exact same problem, i've just installed Windows 7 and drivers
seems to be up to date.
These sudden bursts of noise usually comes when running multiple programs like skype + different games. It might occur twice a day.
The thing is that these bursts of noise cracks my cornea faster than i can throw my headset away. They usually last until i've closed the game / the browser(youtube) and refreshed it and then everything works properly.
I've noticed that turning the volume up or down on youtube when i get the white noise, does not affect the volume of the cracking noise.
Im looking forward for a fix.
BTW im running windows 7 32bit (Didnt have any of these problems with vista or XP)