I'm not sure what to suggest. I got an error 3137 and according to the page it took me to and other pages I've read, most of the answers are the same......remove all USB connected items except a mouse and keyboard and update to the latest iTunes and reboot the system.
Pretty much doesn't seem to matter which error number you get. No luck for me so far either. And, each time you start over, you have to wait for the backup start again. Doesn't seem like anything is easy.