VirtualBox vmdk image corrupt for vbox 0.3.13 ("VERR_VDI_INVALID_HEADER")

The ReactOS-disk1.vmdk image is apparently corrupt. When using the vbox gui to register this file as a new hard disk, the following results:

VMDK: incorrect magic/version in extent header in '/folder/ReactOS-disk1.vmdk' (VERR_VDI_INVALID_HEADER).
VD: error opening image file '/folder/ReactOS-disk1.vmdk' (VERR_VDI_INVALID_HEADER).

Result Code:
0x80004005
Component:
HardDisk
Interface:
IHardDisk

{fd443ec1-000f-4f5b-9282-d72760a66916}
Callee:
IVirtualBox {2d3b9ea7-25f5-4f07-a8e1-7dd7e0dcf667}

When trying the commandline, the error output is this:

$ VBoxManage createvm -name reactos -basefolder /folder/ReactOS-disk1.vmdk
VirtualBox Command Line Management Interface Version 1.6.2
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

[!] FAILED calling machine->SaveSettings() at line 3623!
[!] Primary RC = NS_ERROR_FAILURE (0x80004005) - Operation failed
[!] Full error info present: true , basic error info present: true
[!] Result Code = NS_ERROR_FAILURE (0x80004005) - Operation failed
[!] Text = Could not create a directory '/folder/ReactOS-disk1.vmdk/reactos' to save the settings file (VERR_PATH_NOT_FOUND)
[!] Component = Machine, Interface: IMachine, {f95c0793-7737-49a1-85d9-6da81097173b}
[!] Callee = IMachine, {f95c0793-7737-49a1-85d9-6da81097173b}

When using the commandline to strictly clone the drive, this is the result:

$ VBoxManage clonevdi /folder/ReactOS-disk1.vmdk VDI/reactos.vdi
VirtualBox Command Line Management Interface Version 1.6.2
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

[!] FAILED calling virtualBox->OpenVirtualDiskImage(Bstr(argv[0]), vdi.asOutParam()) at line 3306!
[!] Primary RC = NS_ERROR_FAILURE (0x80004005) - Operation failed
[!] Full error info present: true , basic error info present: true
[!] Result Code = NS_ERROR_FAILURE (0x80004005) - Operation failed
[!] Text = Could not access hard disk image '/folder/ReactOS-disk1.vmdk' (VERR_VDI_INVALID_SIGNATURE)
[!] Component = HardDisk, Interface: IHardDisk, {fd443ec1-000f-4f5b-9282-d72760a66916}

[!] Callee = IVirtualBox,

{2d3b9ea7-25f5-4f07-a8e1-7dd7e0dcf667}