Recently I use disk2vhd  from Microsoft to make an snapshoot and to virtualize one phisical IBM machine.

the problem was that the VHD  that have the boot partition C:  not boots on Hyper-V (Windows 2012 Standard edition)

this is becose the partition was in GPT mode not MBR and in Hyper-V there are some problems:

this problem seems to be corrected on Windows 2012 R2:

the solution:

bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd
This worked for me.