问题：Parent UUID {00000000-0000-0000-0000-000000000000} of the medium 'C:\Users\lin\VirtualBox VMs\NW751\Snapshots/{ef49bb49-eba9-43ad-ab02-21aa20217131}.vhd' does not match UUID {0856fca9-fac8-4320-8f8a-f38029906a1c} of its parent medium stored in the media registry ('C:\Users\lin\.VirtualBox\VirtualBox.xml'

解决办法：首先到virtual VM的安装盘下，我的是D:\software\oracle VM，接着在此处打开cmd命令，执行下面的命令

VBoxManage.exe internalcommands sethdparentuuid "C:\Users\username\VirtualBox VMs\NW751\Snapshots\{ef49bb49-eba9-43ad-ab02-21aa20217131}.vhd" {0856fca9-fac8-4320-8f8a-f38029906a1c}

其中的user name换成自己本机的，最后的 uuid换成virtual VM报错的那个uuid，执行后，如果成功，再次打开虚拟机即可正常开机