Virtual Box UUID {07c3.........} does not match the value {2c1b...} stored in the media registry

Here's what fixed this error for me (using VirtualBox 4.3):

1. Go to File → Virtual Media Manager
2. In the Hard drives tab, you should see a red exclamation point icon beside the disk image you're having trouble with. Select it → Release → Remove → Close.
3. Go back into the settings for the VM and re-add the disk.

To prevent the error in the future, before deleting the virtual disk image files, remove them from the Virtual Media Manager:

1. Go to File → Virtual Media Manager
2. In the Hard drives tab, find the virtual disk you want to remove, select it → Release → Remove → Keep (or Delete if you want to delete it permanently) → Close.
3. Go back into the settings for the VM and readd the disk.

Simply try to rename the virtual disk file.

I had the same issue for a file that was first created thru a VB wizard, then overridden by another tool while cloning another disk. Thus, VB had some uuid assumption for a disk file at a specific path. In my case it was a some whatever.vdi file and renaming it to whatever 2.vdi solved the problem.

Detach the images from your VMs (in GUI or Webinterface)

goto Commandline

"VBoxManage list hdds"

UUID: c153f127-8fd9-4dc2-bc8b-8e39a8bb8238 Parent UUID: base State: inaccessible Type: normal (base) Location: /home/virtualbox/nas4free.vmdk Storage format: VMDK

"VBoxManage closemedium disk c153f127-8fd9-4dc2-bc8b-8e39a8bb8238"

Reattach the images from your VMs (in GUI or Webinterface)