I have an iPod touch with firmware version 1.1.2, and I want to downgrade it to 1.1.1 so that I can jailbreak it. I have downloaded the firmware at http://www.[PIRACY.mu].com/?d=V7H8X2QQ , but when I alt+click on update in iTunes (on Mac), and select the file on the desktop, it reads: "An unknown error occurred (1403)." What do I need to do? Thanks very much for your help.