You might get this weird VirtualBox error if, for instance, you’ve tried to start a virtual machine in GUI mode, but haven’t yet logged into the system graphically. This is most important on headless Linux or OS X systems.
$ vboxmanage startvm "Some Virtual Machine"
Waiting for VM "Some Virtual Machine" to power on...
VBoxManage: error: The VM session was aborted
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component SessionMachine, interface ISession
To get around this make sure you add --type headless to the vboxmanage startvm call, or just use the VBoxHeadless machine starter.