We recently ran across a very interesting blog post by David Ball. He built a Windows XP system using the XenServer Windows XP SP3 template, then used XenConvert to convert it to a vDisk. When everything was done (with no error messages along the way), the vDisk wouldn’t boot. He kept getting the “NTLDR is missing” error.
Turns out that the problem was that the XP VM was created with a FAT32 file system. When he went through the process again, and converted the VM to NTFS before creating the vDisk with XenConvert, everything worked fine.
Nice catch, David!