After remove snapshot, virtual machine got blue screen when boot up

KVM has a much better snapshot capability than what's managed by libvirt; but it depends on qcow2 images. if you use them, just do a savevm <name> on the command console (blocked by libvirt) it won't create a new file, it's a snapshot inside the qcow2 file.

test it first, because some KVM versions have it broken.

If you disable the VSS provider then there is a good chance that you're not going to get a consistent filesystem on the clones. That's one good reason not to do this. Another problem you have here is that you need to be 100% certain that there's no risk that one of the clones will ever come up on your live environment - that will be a very bad thing. If you restore one of those clones in a production environment (ie with any other DC still active) then you risk triggering USN rollback - see this technet article for more info and Zoredache's answer in this earlier ServerFault question.

The best way to handle this is to create another VM, and as JakeRobinson said follow the standard procedures with dcpromo and let it sync itself up. You can keep this online, or keep it mostly offline and let it sync periodically if you wish, but this way you don't run any risk with corrupting the AD databases.