If you downloaded an OS X installer before 14 February 2016, it will no longer work to create new virtual machines. If you use an old installer to create a new OS X virtual machine guest, the installation will appear to proceed as you expect, (e.g., copying files to the hard drive...). Eventually an error message will appear, informing you that the installation is invalid or corrupt.
The fix is to download a new copy of the OS X installer from the App Store. This article explains it all:
Previously Downloaded OS X Installers No Longer Work
This document was generated from the following discussion: Old OS X Installers Will Not Install - Expired Apple Certificate
