I'm fairly new to mobile phones and was wondering if someone here can help me. I've had a nokia 3100 from O2 for about a week and a half now, but have encountered an odd problem, something that only started happening yesterday evening. Whenever I try to access the "Go To" menu, or change any of its settings, the phone blacks out, but doesn't switch off. After a short wait, my background appears again, but it takes a moment for any SIM card functionality to be restored (ie - trying to access my contacts results in a "SIM card not ready" message). This has also happened at seemingly random moments a few times since I got it. Any suggestions as to what this could be?