I can't create a bootable OSX Mavericks Install USB Drive I've downloaded Mavericks from the App Store, repartitioned a 32GB USB key, and followed the instructions. Specifically, I ran:

sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Mavericks.app


Here's the output. As you can see, it fails with an error:

Ready to start.
To continue we need to erase the disk at /Volumes/Untitled.
If you wish to continue type (Y) then press return: Y
Erasing Disk: 0%... 10%... 20%...100%...
Copying installer files to disk...
Copy complete.
Making disk bootable...
Couldn't mount dmg /Volumes/Install OS X Mavericks/Install OS X Mavericks.app/Contents/SharedSupport/InstallESD.dmg (error code 112)Mount of outer dmg failed.
Done.


Help?
It turns out that the Installer Image did not download correctly. To address this I deleted "Install OSX Mavericks" from the Applications folder and then re-downloaded it from the App Store.