Well this is my story (it's kinda weird):

I recently bought a US iPhone with bootloader 4.6 and firmware 1.1.2. It came with a StealthSIM and was Jailbreaked already. Today i decided to install firmware 1.1.3 on it, via installer.app (with the official dev team upgrader). So it went along and eventually I got firmware 1.1.3 up and running. However, my photo's, music etc. were all gone now, so I connected my iPhone with iTunes. Since i have connected my iPhone with iTunes before, it asked me wether i'd like to restore the old synchronisation. So I thought, yay that's much faster than resetting my preferences. Now the thing is, the iPhone does start, but just does nothing at the load screen. Seriously nothing, I can't even turn the thing off. When I connect it to iTunes then iTunes does recognise it, and i can even sync it but it just doesn't do anything at all. I hope you guys can help me out because I'm getting pretty desperate at the moment.. Thanks.