virtualbox.org

Is there a way to make an existing .vdi bootable? A bootable 500 gb HDD (under windows XP) was backed up using Runtime's DriveImage XML onto an external HDD. Next a VHD was created on another computer (Windows 7 Home premium). The backup was then restored on that VHD. At this point the VHD was converted to a .VDI with CloneVDI.exe. When the VDI was booted it gave error message: boot failure or similar to that effect. I tried using UBCD4Windows ( which booted up on the DVD virtual drive) all the information appeared on the vdi, but on several successive retries, the virtual hdd(vdi) disk would not boot. Also I tried MBRfix but this only corrupted all the data.

Impossible to say without being able to see in detail what's on the VHD, how it got there, and why it isn't bootable right now. Any ordinary disk imager would have resulted in a bootable image, so it seems that your backup tool isn't that. A file based backup tool would not catch boot sectors, boot manager partitions, partition maps, swap files, filesystem metadata etc.