Unable to restore Ipad. Unknown error occured (8)

Tried to install 7.1.2 upgrade on Ipad. Upgrade would not complete. Ipad would shut down frequently while trying to use after failed upgrade. Connected it to ITunes where it tried to install upgrade. After several attempts message stated I would have to restore. While trying to restore it fails once it gets to verifying firmware. Error message is "Unable to restore Ipad. Unknown error occurred (8). I've already made sure all updates on PC are complete. Shut down and restarted both Ipad and PC. Even called Apple Support where I was instructed to uninstall ITunes and components. Tried to restore again with same problem.