Ok, so I downloaded and am running the windows version of GP, updated itunes, iphone software, everything. When I put the phone in DFU mode gp just sits at waiting on dfu....
I have tried 3 computers, including a mac. Maybe its not easily jailbroken after all.
Already a thread on it, but make sure you have the most current GP file. It was just updated today. You'll notice it's B4 now, and not B2 (previous release for 4.2.1).
