Hi, I've been using VHDs of Windows 7 booted from my laptops HDD since 5 years ago. Now, I´m trying to do the same in my Microsoft Surface Pro 1 with Windows 8.1. Due to the lack of space, I´m using a microSD for each, in this case, VHDX. From here all is ok. I have been able to install Windows 8.1 in the VHDX in the microSD and boot it up, BUT only once. The microSD is NTFS formated and the partition table is GPT. To make the VHDX bootable, ONCE, I need to do the following from the non virtual installation: Attach the VHDX on the microSD (as drive F Go to F:\Windows\System32 Run "bcdboot F:\windows" Detach the VHDX Restart The VHDX boot option appears as "Windows 8.1 on volume 9". After that, the VHDX boots normally, but the next time it will give an error prior the operating system choose screen, telling that some required file is missing or contains errors: File: \Windows\system32\winload.efi Error code: 0xc000000e After pressing the Windows key to choose another operating system, the VHDXs entry appears as "Windows 8.1 on volumen 7, from Surface.vhdx". This seems OK for me, more than the "volume 9" text, but it is unable to boot and always give the error regarding the missing file. Anybody knows what could be the problem? Best Regards.