I have had this problem a couple of times recently, it may be a google voice thing or maybe a phone thing. I have found that the phone gets realyl crazy sometimes when I try and answer. It's as if the proximity sensor goes into reverse or isn't working. When I bring the phone away from my face the screen goes off. I try to turn it back on with the on/off switch and the back and the screen will turn on briefly before turning off. It's especially bad when you are on call and try switching to another incoming call. I have to take the phone away from my cheek to switch over, the screen will flicker on and then off and generally behave erratically. It doesnt help that google voice asks me to press to confirm I want to take the call since I have to wait for the screen to turn back on so i can press keypad and then press one to confirm..