I have not currently oc'd, phone is recently flashed with some programs installed. I even tried to flash the phone and not to install anything, just used built in skype. Even with nothing installed the no SIM icon still appeared and I sent the phone to repair center - they did not fix anything, because the didn't happen to them. But I didn't use the phone for 3 weeks and it for few days it was ok. I think, that this is somehow connected to heat production of the phone, some parts may be overheated and it's connected to signal strength. When I was in Prague (connected to 3g), I didn't get this error all the day, even when the baterry was low, but on the way from Pilsen to Prague it happened repeatedly. Signal was not weak (100% all the time), but it had to be somehow bad, so the SIM contact was lost. I'm not really sure why this happens and can't even reproduce situation, when the error happens at 100%. It just happens randomly, which is weird.