When I want to update my iPhone 4 to iOS 5, it first makes a backup which takes a long time. After that, it gives the error ''this device isn't eligible for the requested build'' and I'm done. How can I fix this? I have searched and read about it, hosts file (which I can't replace), reboot my iMac, my iPhone, it just isn't working. Damnit, I want iOS 5. My iMac has all the new software: Lion, new iTunes, etc. My iPhone is running 4.3.5 tethered jailbreak... Please help!