WS2008-R2 Add Roles Hyper-V cannot be installed..

When trying to automate the build/deployment of Windows Server 2008 R2 Enterprise Edition (Full install) using scripts for adding roles and features beware using “start /w ocsetup Microsoft-Hyper-V” as this may break your server from successfuly performing a Hyper-V install..

If you do use that script then something (quite a lot) happens and various components appear to be installed including a restart.  Don’t be fooled in thinking Hyper-V has installed as when checking, Hyper-V isn’t listed as an installed Role and the management tool is not installed…

Later attempts to use the Add Roles Wizard to add Hyper-V reports it cannot be installed, giving this error dialogue:

Hyper-V-cannot_install

The processor on this computer is not compatible with Hyper-V. To install this role, the processor must have a supported version of the hardware-assisted virtualization, and this feature must be turned on in the BIOS.

eek!  but my x64 bit server has hardware virtualisation support hasn’t it..?!?!?   of course the answer is yes, but this what you will see on a box that hasn’t.

After rebuilding my test platform I realised the fix to this was to revert the attempted Hyper-V scripted install by using:
start /w ocsetup Microsoft-Hyper-V /uninstall
Allow the Windows Optional Component Setup dialogue to restart when prompted

Hope this helps save you a rebuild!