Disk2vhd, bootmgr is missing. Missing operating system.

Os adjunto este procedimiento para hacer funcional un vhd exportado desde disk2vhd de Microsoft

PROBLEM:
- Not booting, displaying error “Missing Operating System”

Part1:
1.- open Disk Management
2.- Go to the Menu, select Attach VHD and browse and select your VHD File.
3.- Disk Management will attached as “Primary Partition” .
4.- On Disk Management right Click on the VHD HDD and select “Make Partition as Active”. You will see the VHD “Active, Primary Partition”
5.- Then Right Click on the Left Hand Side HDD (on top of Disk0 or Disk1 or wherever is your VHD placed) and select “Detach VHD”. Make sure the “Delete the virtual disk after removing the disk” is UNSELECTED otherwise will delete the VHD file.

Now…once you try to boot from Hyper-V, the error will change to “BOOTMGR is missing”

Part2:
1.- Now, place the Server 2008 R2 Installation Disk
2.- On Hyper-V, double tab the VHD and go to the menu Media, capture Drive E: or the letter of your drive.
3.- Make the VHD on Hyper-V boot from your CD
4.- Once it load, select the Language Options and the Select Repair Option. If you don’t see Select Repair Options, select Next, then cancel and at some point will display the “System Recovery Options” with the Command Promt.
5.- Open Command Promt and it will land on x:\
6.- Cd to the folder and type “x:\sources\recovery\StartRep.exe”.

That will fix the MBR and place everything is place for your VHD to boot. Do it twice is necessary, sometimes the first time do not do it.