Yeah id do what Trekker said! Coz i was havin d exact problem and then one time when the phone did go off it wouldnt come back! i Couldnt even get it to power on anymore! so when i braught it to the O2 shop they said it was the firmware and just updated it! Works fine now! Bad thing was..i lost all my tones and pics!

Try upgrading your firmware. take it to O2 and they should do it for free.

maybe something is loose; or you could look under phone settings in your menu and see what memory is set to be in use, i.e. sim card, phone, or both.

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?