Virtualbox Error

I tried to copy a .vdi of one container to use in another one, basically to clone instead of having to install the OS again.

Failed to start the virtual machine Centos 5.5 Mirror.
Medium '/home/testuser/.VirtualBox/HardDisks/Centos 5.5 Mirror.vdi' is not accessible. UUID {a1a9fad7-0402-4867-b8f3-39fb49454bc5} of the medium '/home/testuser/.VirtualBox/HardDisks/Centos 5.5 Mirror.vdi' does not match the value {4945a0e8-0ed5-4736-9088-bcaf7b9d07f1} stored in the media registry ('/home/testuser/.VirtualBox/VirtualBox.xml').
Method GetVRDPServer is not implemented.

This command gives it a new UUID, but that's not the problem, I get the same message as above.  VBOX has a certain UUID associated with this .vdi name stored an .xml file

vboxmanage internalcommands sethduuid "Centos 5.5 Mirror.vdi"

Sun VirtualBox Command Line Management Interface Version 3.1.6_OSE
(C) 2005-2010 Sun Microsystems, Inc.
All rights reserved.

UUID changed to: bd57d074-a562-4712-bf44-892441215720

The final solution was to go to "File -> Virtual Media Manager" find the .vdi and click "Remove", then add it back to the Virtual Media and choose it as the boot device for your Virtual Machine.