Everytime I power off my X2 & turn it back on I get a message in the notification box that says, "MDN changed, please check pin." Not only do I get that message, 1 of the other phones on my acct gets a text message that is automatically sent from my X2 that says, "New Sim Card, please check pin." Also, when I try to use backup assistant after I enter my pin, once again I get a notification that says, "MDN changed please check pin." Maybe I'm completely mistaken but where is their a SIM card in a Droid X2? Anyone with any advice on how to fix this problem? I would greatly appreciate your input. Thanks a lot.