If you cannot open the guest session and get a VERR_NOT_FOUND VirtualBox error, follow the tips, solutions, and workarounds mentioned below. Check if “VBoxGuestAdditions.iso”n exists Insert ...

Also looking inside the memtest86-iso.iso file, I don't see anything I recognise as characteristic of bootable media e.g. it doesn't look like a linux bootable or a windows bootable..

How to Open VMDK in VirtualBox. VirtualBox is an open-source computer hypervisor software package maintained by Oracle. VirtualBox is capable of running on multiple platforms and handling ...