My iPhone 4 4.2.1 won't jailbreak on Greenpois0n, no matter the version. It jailbreaks and everything runs fine. Until it gets to the animated boot logo. The logo runs fine for a few seconds then it twitches, resulting in my phone crashing, rebooting (with the normal apple boot logo) then going to the "Connect to iTunes" screen and forcing me to restore my iPhone. Any help would be greatly appreciated. If there is a way I can fix it or an alternative FREE jailbreak software opposed to Greenpois0n. Thank you.