[Mystery]

Something like this happen to me two days ago. I received a text message so I turn on the screen, and when I was sliding down the lock screen I received another text message. The slider was stuck half way and the screen turned off. I tried turning on the screen and pressing all the buttons but nothing happen. I received another text and I could hear the ringtone but the screen just wouldn't turn on. The four bottom buttons were lighted up. I was gonna remove the battery but couldn't remove the battery cover. lol Then after like 10 - 15 minutes the phone restarted it self and I haven't had any problems since.