So lately due to the 4.2.1 there has been a lot of iPhone users saying there iPhone got stuck in recovery mode. Well this happening because these "users" are new to jailbreaking or aren't completely getting the whole picture. The jailbreak Redsn0w for 4.2.1 (created by the iPhone Dev Team) is tethered. Tethered meaning after your iPhone reboots, you turn it off/on or the battery dies you need to run Redsn0w in tethered mode. Uncheck everything listed in Redsn0w except boot tethered. Some users are seeing Cydia as a white, blank icon and they reboot their iPhone and it gets stuck in DFU mode and they restore! <--Bad idea. You don't do that! Or they re-run the jailbreak. Running the jailbreak over an already jailbroken iPhone is (my dubbed, maybe?) iPhone Suicide! After seeing the white Cydia icon, you then have to re-run Redsn0w in tethered mode. Then! After your iPhone reboots, Cydia will be working normally. If you need the unlock install ultrasn0w <--will require reboot. If you have to restore your iPhone for any reason on 4.2.1 you have to use a custom ipsw. iTunes will just give you an error message because your baseband is now that of an iPad if you don't use a custom 4.2.1 I hope this clarifies some issues for iPhone users. If you have questions, reply here (I'm sure AppleJuiced will be in here. He can help as well).