VBoxManage error - cannot register hard disk

[TRAyres]

VBoxManage.exe: error: Cannot register the hard disk 'X:\Centos64\Centos64.vdi'
{de0665e2-936b-41c5-b571-9b348d16ee54} because a hard disk '\\DiskStation\Virtua
l Machines\Centos64\Centos64.vdi' with UUID {de0665e2-936b-41c5-b571-9b348d16ee5
4} already exists
VBoxManage.exe: error: Details: code E_INVALIDARG (0x80070057), component Virtua
lBox, interface IVirtualBox, callee IUnknown
VBoxManage.exe: error: Context: "OpenMedium(Bstr(pszFilenameOrUuid).raw(), enmDe
vType, enmAccessMode, fForceNewUuidOnOpen, pMedium.asOutParam())" at line 178 of
file VBoxManageDisk.cpp

[noteirak]

Cannot register the hard disk 'X:\Centos64\Centos64.vdi'
{de0665e2-936b-41c5-b571-9b348d16ee54} because a hard disk '\\DiskStation\Virtua
l Machines\Centos64\Centos64.vdi' with UUID {de0665e2-936b-41c5-b571-9b348d16ee5
4} already exists

Did you move the file recently? If so, make sure you remove it from the Media Manager.

[mpack]

... and remember to shut VirtualBox down completely for 30 seconds or so after removing the disk, before adding it back.

ps. It is a bad idea to locate a disk outside the VM folder. Relocating the entire VM folder would have been better.