I've noticed a strange thing that happens on my MacBook Pro every night at midnight. At first I didn't realize it was happening at a specific time until I was up two nights in a row and happen to notice the time.

At midnight (or a few seconds after), my MacBook Pro goes through the EJECT motions all by itself. You know the sound you get when you press the eject button and there is no disc inside, but the SuperDrive goes through the motions anyway? Well mine does that on its own every night if the drive is empty. I haven't confirmed it yet, but I'm pretty sure that if there is a disc actually in the drive, it doesn't do anything. I just have to purposely test this maybe tonight If I think about it.

Any reason why my drive thinks it needs to eject a disc every night at midnight?

apparently I'm not alone.