Hey, my iphone 16gb 3gs has started to have a problem. when i am in apps/sending an email/ in settings changing wallpaper or internet settings it keeps going back to the home screen. i have tried turning the phone off and back on but the problem still persists. i have had a look around the net and people are sying to plug it to itunes and reset to factory deafaults. if i do this will i loose my jailbreak? or will my firmware change to the newest??