I have personally restored a lot of iphones and ipods. I have never heard of an error 9 and it may sadly be a hardware issue, especially since you have switched computers, usb ports..etc. Maybe try downloading tinyumbrella and use the kick out of recovery option. there is also a program for windows that does this. This will kick the iphone out of recovery and may fix your need to recover all together. Give it a try anyways.