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Why do I receive a Missing Operating System error after I reboot my machine?

A. Unless your computer has suffered a major disk malfunction, this error message usually means that the hard disk's active partition has changed. To resolve this error, perform the following steps:

  1. Boot your machine using a Windows Me, Windows 9x, or DOS 3.5" system disk that contains the Fdisk utility.
  2. Start the Fdisk utility.
  3. Press the Enter key to enable large disk support.
  4. Select Option 2 for "Set active partition."
  5. Enter the number of the partition that you want to set as the active partition, and press Enter.
  6. Press the Esc key to exit.
  7. Remove the boot disk from the floppy drive and reboot the machine.
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