Hi All, I have a JB'd 3GS, my brother a JB'd 3G. We wanted to swap, but I wanted to clear everything off the phones first and start new. Went into to settings > general > reset > erase all files and settings. I did this with both phones. Each went to the black screen with an apple logo and a progress indicator below, then eventually made it to the black screen with apple logo. And then sat there for more than an hour. I'd finally had a enough of it, and decided to just DFU them and reupload the JB'd firmware (I'd just upgraded them to 4.2.1 with pwnagetool less than a week ago). Problem is, now when I go into iTunes and try to restore using the custom firmware, iTunes tells me that the iPhone could not be restored. "An unkown error occured (1600)." Any thoughts on what could be afflicting me?