you may have the option checked where the volume decreases as you move the phone to answer it. Go to 'settings' then 'sound' then it will be under 'incoming calls'. The selection is called 'quiet ring on pickup' and it does just that.. quiets the ringer when you pick up the phone.
MAINFRAME, read your review. Don't waste your time with the nexus. Other than that screen and ICS, its not worth it. I went back to my rezound after using the nexus for 4 weeks. I've never dropped so many calls or lost data connections so easily. I was happy with the rezound before the nexus dropped, now I'm even happier after using the nexus.