I seem to be the only one having this particular issue with the Captivate. With a new sim card i have 3G, take it home and put it on wifi overnight, and the next day i cannot get 3G. have done reboot, soft reset, master reset, toggle flight mode off/on. The only thing that gets 3G back is another sim card. I have gone through 2 phones and 4 sim cards with this. Samsung support is scratching their heads, any ideas from the android community?