When provisioning a Windows 7 or Server 2008 R2 virtual machine from a WIM image, the virtual machine fails to boot with an error message that he BOOTMGR is missing.
A WinPE boot disk of the proper bit type (a 32-bit operating system can only be repaired using an x86 version of WinPE). Or the installation media that matches the installed operating system.
If a virtual machine is created from Windows 7 or Server 2008 media as a default installation, the installed virtual machine can be made from a template, or copied. But it cannot be imaged with ImageX and then deployed from that Windows Imaging format (WIM) image.The ImageX /capture process to create a WIM only captures a volume not the entire disk. Therefore the new System Reserved partition containing the boot information is not captured.
According to Microsoft TechNet documentation How to Perform Common Deployment Tasks with Virtual Hard Disks you must use BCDBoot.exe to “configure the boot entry in the BCD store to be on the volume inside the VHD.” If you follow the link, the portion that you are concerned with is: “Prepare a VHD image to boot inside a virtual machine.”