Missing operating system

It's possible the code is damaged in the MBR (Master Boot Record) or the partition table is damaged. While the code can be easily fixed, a damaged partition table may not be repairable.

If you have a graphical partitioning boot CD, such as Partition Commander, System Commander, Fix-It Utilities Professional or SystemSuite Professional, we suggest using it. These tools can validate the partitions, it's fast and it can fix a some issues not possible with the Windows solutions. Using these tools, you'll replace the MBR with a Generic MBR (In manual partitioning, Advanced). You'll also make sure the one partition with your OS is set bootable. Click on the OS partition and check Under the General tab. It should be marked as Active. If not, go to the menu Advanced, select Set/Toggle Bootable/Active. Under the General tab, you should now see "Active". Remove the boot media, exit and reboot.

You can also replace the MBR from a command prompt. You'll need to boot from the Windows CD/DVD and go into the 7/Vista Recovery Console or XP Recovery Console and select Command prompt. Follow our instructions under recovery console to repair the MBR (instructions differ between Windows 7/Vista and XP).

Replacing the MBR does NOT change the partition table, so if it's damaged, it will not be fixed.

Once working, be sure to do an extensive scan for viruses and malware.

If you are booting from either a DVD, CD, diskette or a USB drive, remove the media and boot from the hard disk. The media is either damaged or is not intended to be bootable.

Windows provides tools to install a new partition boot record. Doing this does not erase any operating system files or your personal data. If this is the only damage, it has a good chance of fixing the problem, but if additional system sectors are damaged, recovery will be very difficult if not impossible.

1. To reset the Windows boot sector, boot from your Windows installation CD/DVD.
2. Go into the 7/Vista Recovery Console or XP Recovery Console and select Command prompt.
3. Follow the instructions in our guide under recovery console, command prompt to repair the boot record (instructions differ between Windows 7/Vista and XP).
4. Exit and reboot.

The BIOS may be configured to boot from the wrong device. If you suspect this, the device boot order can be changed in the BIOS setup. Be aware there little consistency in BIOS setup operations, even with the same manufacturer on different models. As such, these instructions are bit less precise than we'd prefer.

1. Reboot and enter the BIOS setup. Often the BIOS displays the correct key to use briefly on screen or you may need to refer to the computer's user manual. Typically you hold down the Del, Esc, F1 or F2 key immediately after booting. The setup key can also be found in our BIOS access list.
2. Look for a section on Boot or Booting. Often this appears on top menu. Select the Boot option, and if necessary the Boot order choice. The Boot order choices should list the order of boot devices. Typically the CD is the first boot device with the hard-disk typically second. The diskette may also occur before the hard disk, which is acceptable, although this will slow your hard disk boot by a few seconds. Avoid USB and network boots before the hard disk unless you know for sure you are using them (which is exceptionally rare).
3. Save and exit the BIOS. It will force a reboot. See if this change corrects the issue.

If you had changed, added or removed hard drives, or changed or removed drive cabling, likely something is wrong. Recheck that the drives are properly installed and the cabling has not changed. Switching cables to different motherboard connectors or changing the master/slave drive jumpers (on old ATA drives) can cause this problem. In some systems, the cables were not plugged into the drive or motherboard securely and may have worked loose. Reseat all drive connectors.

It's also possible a hard drive is failing. Use a system diagnostic to validate the drive or swap to another hard disk.

Several software products that offer disk diagnostics includes Fix-It Utilities Professional and SystemSuite Professional. Other diagnostic products include Eurosoft's PC Check and Iolo's System Mechanic.

If you skipped any of the prior solutions, you may want to return and try them out. These next options are when all else fails!

• Remove the system hard drive and replace it with a blank drive. Install a fresh copy of Windows. If this works, it's unlikely to be a hardware issue. At worse, it may be time to start over with a fresh copy of Windows, although reinstalling your applications may make the problem reoccur.
• Send the PC in for repair - someone else can deal with it!
• Time for a new PC?
• Consider a MAC, but wait - they can have similar hard-to-solve issues and you'd have to buy all new applications.
• Use your PC as a boat anchor and go for a drink.

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