Help! For about the last 45 minutes, my iPhone 3G has been switching itself on and then after about 10 seconds going to the "slide to turn off screen", then back to the menu and then back to the "turn off" screen... Even if I do turn it off it switches back on again after a few seconds. A full restore didn't help, though it's just re-syncing my iTunes library and looks like it might have settled down again. Has anyone else experienced this or know what could have caused it, or if it's likely to recur? Thanks - very worried!