when i try to turn the volume for my ringer/calls up or down [on the side buttons on my phone], my samsung GI freezes up, black screens, and does a sort of reboot. not completely turning off the phone but it doesn't pop up the applications on my screen right away, it does sort of a loading screen. the buttons work properly when trying to change the media volume, and the notification noise works fine. its just the volume. so now, i have no idea when im getting calls. does anyone know how to fix this? should i take it to my mobile store? should i call the company? any tips at all would be useful. thank you.