There is new version (1.3) out. That version solves problem with booting of some machines. Just retry whole process with new disk2vhd.
This update to Disk2vhd makes more Windows XP and Windows Server 2003 VHDs bootable by updating their MBR and boot sectors to be compatible with Hyper-V and Virtual PC and by installing the Intelide driver if it it’s not already installed. It also optimizes image creation by not copying paging and hibernation files.