I unlocked my Captivate a few days after the unlock came out and have been using it flawlessly for the last month or so. Well, my extra batteries came in last night so I kept taking the batteries in and out, powering the phone on and off. Then I used the new battery 'til it died and when I turned it back on, the SIM lock was on again. So I had to go through the process this morning again to unlock it. Tip: don't power on and off your unlocked Captivates too much/frequently. It'll lock up again!