I have mucked up one Xbox already through modding and thought I had been successful with the latest. It worked well after using xboxhdm 1.9 but I did not back up anyting as I did not know how to use FTP and was going to find out. Turned it on yesterday and got error 21. Tried hotswap using X Box 360 program and while I was building Partition 3 with new dash, the PC faltered and the next I knew was that Partition 4 had disappeared. Obviously the drive will not work without this partition and I do not know how to get it back other than rebuilding using xboxhd. My feeling is that if I do rebuild the drive, which will wipe the hard disk, it will not be built correctly because I do not have the eeprom which I believe would have been in the now non existent Partition 4. Has anyone any ideas please?