Error code 9 points to a USB error. http://support.apple.com/kb/TS1286 is the article for USB troubleshooting. You should also verify that you have disabled (or removed) any security software for the time necessary to perform the update.
Bit of background so I don't waste anyone's time:
IPhone 4s, itunes 11.1 (both on computer and iphone)
I too am stuck in this recovery loop. I've read all over the community and have tried the suggestions:
I put my phone in DFU mode & also recovery mode (a.e. hold home/sleep button down for 10 seconds, etc., etc., etc.) and tried restoring this way 10 different times, as some posts say it sometimes works after the 4-5 try but still no results.
On my Iphone Screen the apple logo appears and the status bar below it gets stuck about 2/3 of the way, then I get the following error message, "could not restore because of unknown error (1)".
I set up an appt. at the apple store for tomorrow, but holy sh*t what a fiasco!