Most of you have been getting errors when trying to restore your iDevices with Custom IPSW files on Windows. The reason why is because your device must be EXPLOITED before you can restore with a Custom IPSW. For MAC users this is normally done via PwnageTool by selecting the "DFU MODE" option. Once you put your device into DFU Mode, PwnageTool will then proceed to upload a special Payload that will put your device into a "Jailbreak+DFU Mode" allowing you to restore Custom IPSW's via iTunes. But now with the new version of iREB, Windows users can do this as well!
iREB 4.0.x-4.1 RC2 will allow you to put your device into a LOW LEVEL DFU+Jailbreak Mode allowing you to restore your iDevices using Custom IPSW's on Windows via iTunes. This is the same method that is used in when you select DFU Mode in PwnageTool. This is different that just the normal DFU mode as this basically uploads a special payload while you are in DFU mode that allows you to restore your device using Custom IPSW's without having to worry about any errors in iTunes!