Restore Errors/31xx

Error 3123
Something dealing with movie rentals.

Error 3191
QuickTime may be corrupted. You must reinstall it before iTunes will work. Windows users, also try turning off Compatibility Mode for QuickTime
 * 1) Right-click on   (  for 64-bit Windows) and choose Properties from the shortcut menu
 * 2) In the Properties window, click on the Compatibility tab. Deselect the checkbox labeled "Run this program in compatibility mode for"
 * 3) Select "Windows XP"
 * 4) Click Apply
 * 5) Close the Properties window

Error 3194
Occurs when trying to install an old firmware and Apple's server disallows the installation. The only solution is to have the SHSH blob backed up and modify the hosts file to point to Saurik's Cydia Server where they are backed up (or localhost if you have it yourself). Also happens if restoring to the latest iOS and the hosts point to Cydia. Remove gs.apple.com lines in hosts file.

Error 3195

 * There is no SHSH blob for the firmware.
 * This is the same as "This device isn't eligible for the request build." but with an cache error.