why does my asus laptop keep making the sound of someone plugging in or unplugging a usb device?

I dont know why it does it but i thought it might be because my cd drive is messing up like i have to enable my dvd cd drive everytime i boot it up and i am wondering if the sound is coming from it being disabled and enabled…plz help thanks
well i know its not a external device because nothing is plug into the usb so…and why does my dvd drive keep getting disabled?