Every so often, the screen on my phone refuses to turn back on from standby mode. I'll push the power button and the four buttons below the screen light up, but the screen does nothing. I have tried waiting for a long time and pushing all of the buttons, but the only way I have found to make it work again is to pull out the battery, put it back, and let the phone boot up again. At first, I thought that the phone had completely crashed when this occurred, but I'm seeing more and more evidence that it is still running, only with no display. Once, I noticed this just as a call was coming in. The phone continued to play my ringtone, but the screen did not display anything. I tried touching the screen where I thought the answer button should be, but that didn't do anything. I have read stuff online suggesting that an app called Juice Defender can cause a quite similar problem, but I don't use Juice Defender and never have. Any other suggestions would be welcome, as this is highly annoying. Thank you.