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#21
Most times when you move a HD with Win7 to new hardware it will not start up due unless first SysPrepped on the old hardware: SysPrep to move HD to another computer
In a case where the old hardware is dead or not available, the transferred HD or image can be started by first booting Paragon Adaptive Restore CD to run on the installation.
If the same problem occurs when trying install in your brother's computer then you need to confirm the ISO integrity, download another from a known safe source, then burn to DVD using ImgBurn at 4x speed or write to flash stick using Universal USB Installer.
"Bootmgr is missing" means the DVD is not being booted, but trying to start the HD. Make sure you are booting the DVD or flash stick correctly: How to Boot your Computer from a Bootable CD or DVD
or use the one-time BIOS boot menu key given on first screen to select DVD/USB drive.