Windows Guest: unable to open .cdr image

[valenceelectron]

Hi.
I created a .cdr image with Disk Utility and saved it to ~/Desktop. There was no problem embedding the image as CD into my Windows 7 guest and it's still working. After moving the file to some other location on OSX the following pops up upon embedding:

Code: Select all

Failed to open the CD/DVD image /Users/Julian/A.cdr.
Could not get the storage format of the medium '/Users/Julian/A.cdr' (VERR_NOT_SUPPORTED).

Result Code: 
VBOX_E_IPRT_ERROR (0x80BB0005)
Component: 
Medium
Interface: 
IMedium {29989373-b111-4654-8493-2e1176cba890}
Callee: 
IVirtualBox {3b2f08eb-b810-4715-bee0-bb06b9880ad2}
Callee RC: 
VBOX_E_OBJECT_NOT_FOUND (0x80BB0001)

I don't get it cause it's the very same file. The only location not resulting in the above error is ~/Desktop (the filename must not be changed or ~/Desktop will error too). :/