Hyper-V

You should be aware that on some older hardware when you install Hyper-V and it modifies the boot sector that it can make it so the physical hard drive isn't found and won't allow you to boot to the Parent machine. This can be fxed by using bootsect.exe from a WinPE boot device. http://technet.microsoft.com/en-us/library/cc749177.aspx

I wish I knew this before I needed it.