Default [Q] Bug on 4.1.2

Hi guys, I have an optimus g e975 running stock 4.1.2 here, and I'm waiting for the official KitKat update but have anyone of you encountered the problem that when you long hold the power button on the phone, the reboot menu does not show up? My power button works, but only to lock the phone and restarting the phone is impossible cause I can't long press the power button. Anyone else encountered this problem and anyway to solve it? This problem occurs randomly and sometimes the reboot menu shows up, sometimes it doesn't.