Hi, I have a jb iphone 4 on 4.2.1 and randomly it started to restarting. Sometimes it just shuts off and it wont turn back on, I have to hold the home and sleep button so I can start the phone. While I am using the phone, it won't restart but as soon as I turn the screen off after few mins the phone is off. The last app that I downloaded was a theme called "cups color", I also deleted that and few other apps that I downloaded right before this happened but nothing helped . I dont want to restore does anyone know what can I do ?