Hello, I have an iPhone 3GS that I am going to jailbreak/unlock for a friend. I want to use 4.3.3 to do this so I downloaded the stock firmware and alt/restored it in iTunes. After a few seconds it pops up with this error. I have 2 Macs and 2 Windows (7) computers available to me but I can't seem to get it to work on any of the computers. Why won't it let me simply restore? It should be simple enough, I've done it 100 times in the past and this iPhone 3GS has never even been jailbroken before. I put it into DFU mode, etc, but nothing seems to work. I would really appreciate any help!