i came from a 3G and still have the 3G simcard in my captivate. Every once in awhile (at starting to happen more often), whenever i power down my phone to change the battery or just reset it, it'll come back on with the no network sign on the notification bar. Sometimes i literally have to reset my phone about 10 times for it to recognize the network. Anyway, my question is.....are any of u previous iphone users still using the same simcard. If so are u having problems after boot up?