When using VMPrep to setup a VM for use in a Lab Management system I got the error cross at the bottom of the dialog
Not too much help, usually there is a link to the log file or a message.
If you look in the log file in c:user[name]AppdataRoamingLMInstaller.txt you see that the path to the Patches folder is invalid.
This is fixed by editing the VMPrepToolVMPrepToolLibraryApplications.XML file and correcting the path (which I had made a typo in)