I have a HL-DT-ST DVDRW GA32N Superdrive in my 2010 i7 iMac and I've had to reinstall the OS twice, because someone in the house kept messing with different files. Anyhow, the first time I installed it the superdrive was very loud, as it was the second time I installed it. It was like a loud vibration, as soon as I put the disc in. I have put other discs in and they are as quiet as can be. I've tested 9 or 10 discs and they all seem to be quiet. So I decided to put in the install disc one more time and it was quiet as well, no more vibration. Is there something wrong here or are these drives just noisy sometimes?