I got my SG II yesterday. It worked perfectly for one day. . I installed some apps and games from android market. . I switched off phone today and tried restarting it. . It started but when screen timer ran out, it refused to start again . . I need to remove battery and restart it again . . but same thing happens once screen timer runs out. . But, when I remove smart (sim) card, it works perfectly. . what could be the problem? any suggestions ? Thanks !