No SIM message on iPhone 4
More detail:
First error was seen around 5:30PM (EST) yesterday and restarting once fixed it. Second time was around 9pm, that time I had to restart three times to get signal back. This morning it happened again around 10am. It is nearly noon now, haven't seen it again so far but I am sure it will happen again... paranoid about missing calls now!
MacBook Pro & iMac, Mac OS X (10.6.4)