Shutting the sever down seems the best way to go, but given that Server Core is the window-less version of the OS, the shutdown command needs to be issued from the command-prompt. Unfortunately, I’m lazy and can’t be bothered to log-in just to shutdown….

I’ve recently discovered that Server Core will shutdown cleanly when sent the VirtualBox shutdown signal, issued when closing the VM – to bring up the Close Virtual Machine dialog (shown below), simply close the Window the VM is running in, type [Host Key]+Q, or issue the Machine->Close menu-command:

Select the ‘Send the shutdown signal’ option and click Ok (the VM sometimes doesn’t respond to the first attempt, but the second attempt is usually recognised).

Windows Server 2008 Core will kindly oblige and shutdown cleanly.