yah don't release the keys until the phone has shut off. It will only take a screen shot when you lift your fingers

 

i've found that it won't take a screen shot if you press the volume down key first and then press the power key. obviously you have to hold both down to get it to reboot. but pressing the volume down key before starting to press the power button has worked for me

 

I don't mean to be rude but this information is wrong. Letting the buttons go has nothing to do with anything.

Pressing PWR&Vol- (at the same time) will take a screen shot after a few seconds. A few more seconds after that and the phone will hard reset(simulated battery pull) If you are wanting to do the hard reset, and do not want to take a screen shot, then CooperLA1 is correct. You must not press them at the same time. Press and hold one, then a split second later press and hold the other. Then hold until phone resets. It doesn't matter which you hold first, PWR or Vol- As long as they aren't pressed together and held long enough, your phone will reset without a screen shot being taken.

 

Your right and its ok I was totally wrong on that. thanks for clearing that up.