You could start by telling us the specifications of your VM and the host system. Is it VMWare or some other technology?
Bear in mind that DOS is ancient and may not be able to handle the virtual machine's allocated hard disk size, nor the way that memory is managed.
Simplest solution is to build a WinPE boot disk or boot iso file using the Ghost 3.0 tools and use that instead. Forget DOS once and for all as it is the author of all your misfortunes.