After installing Windows 7 and Vista with multiple hard drives installed, I often find this error after restarting the computer.
BOOTMGR is missing. Press <ctrl>-<alt>-<del> to restart
This is caused by another bootrec being present, usually on another hard drive than the one that Windows is installed on.
To Fix:
- Disconnect all hard drives
- Boot with Windows Installation disc
- Select "Repair your computer"
- Choose "Startup Repair"
- Verify the computer boots without installation disc
- Turn off computer and re-connect hard drive(s).