How can I check the uuid of a vdi or vmdk?
There should be some command line on VBoxManage to show it.
I know I read it some place in the docs, but now for some reason I can't find it...
Run VBoxManage and pass it showhdinfo and your VDI:
VBoxManage.exe showhdinfo "c:\MyMachine.vdi"
VBoxManage list vms will list the virtual machines and their uuids without having to know the path to the particular vdi.