Sent from my iPad
iOS 4.2 FAQ:
I had the same frustrating problem. The fix was easy.. Go to apple support to change your apple ID password. After changing password, Log out on itunes, then log back in with new password, then sync device. Small pain in the ass, but it worked.
Go to apple support and change your password. Log off in itunes, then log back in with new password. Then sync. IT WORKS!