hello! i've been having an issue where my physical keypad and the navigation buttons will not stay lit when i'm using the phone in lo light situations. i have to hit the power button a few times or open/close the slider [doesn't always work]. i've seen a fix on this forum where you turn off 'vibrate on key press' and 'clear learned words' etc and i have done these measures but it doesn't seem to have worked for me. any suggestions? thank you!