The error message you list is from VMware and not from Virtualbox.  Those are 2 different virtualization applications which expect the Linux operating system virtual machine disk image file to be in different formats.   As far as I know, it will not work to run the Freesurfer VirtualBox VM as is using a VMware application.  The .vdi disk image file we provide as part of the Freesurfer VM download needs to run in the Virtualbox application..

Do you have both a VMware application and the VirtualBox application installed on your machine?  If so -  and using VirtualBox to run the Freesurfer VM causes an error to be generated from the *VMware* software, then there is probably a conflict between the 2 applications.  In that case I would uninstall all the VMware software and try running VirtualBox again.

- R.