1. Power down the source virtual machine.
2. Boot the virtual machine using the Windows Server 2008 R2 .iso file.
3. In the Installation Wizard, select Repair your Computer.
4. Select Command Prompt.
5. Run these commands in the specified order.
diskpart
list volume
select volume 1
attributes volume
attributes volume clear nodefaultdriveletter
6. Restart the virtual machine after removing the mounted .iso file.
7.Clone the virtual machine again
Autochk program not found - skipping auocheck
原文：http://blog.51cto.com/549687/2089933