Fix MBR

Category: Hard Drives , Windows

"I was trying to fix a spyware problem and it seems I messed up my computer. Now when I start Windows XP, I get the 'MBR Corrupt' and 'Error loading operating system' messages. What should I do?"



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Got a Damaged Master Boot Record?

master boot record
Although those messages sound pretty scary, there's a good chance your hard drive is still intact. In most cases this problem can be fixed with a simple procedure that repairs your Master Boot Record (MBR). When you start your computer, the BIOS (basic input/output system) looks for the MBR on the first sector of your hard drive. The MBR tells the BIOS which partition on the hard drive contains the operating system.

So... if the MBR is damaged, the BIOS can't locate and start the operating system. When your BIOS detects a damaged MBR or boot sector, you'll see ominous messages like Invalid partition table, Error loading operating system, or Missing operating system. In some cases, dark clouds will apppear on the horizon, and you may hear the distant rumble of thunder. But fortunately, the Recovery Console offers some tools to help clear up the problem.

Repairing a Damaged MBR

Your Windows XP setup CDROM has a tool called the Recovery Console, which is designed to help you repair a damaged master boot record or boot sector. To start the Recovery Console and fix your damaged MBR, follow these steps:

  1. Restart your computer with the Windows XP Setup disk in the CDROM drive.
  2. If you are prompted to press a key to start the computer from CDROM, do so quickly. Otherwise it may try to boot from the hard drive.
  3. After a few minutes, you'll see a prompt to press the R key to start the Recovery Console.
  4. When Recovery Console starts, it will prompt you to enter a number corresponding to the Windows XP installation that you need to repair. In most cases, you'll enter "1" (which will be the only choice). If you press ENTER without typing a number, Recovery Console will quit and restart your computer.
  5. Enter your Administrator password. If you don't enter the correct password, you cannot continue.
  6. At the Recovery Console command prompt, type fixmbr and then verify that you want to proceed.

Your damaged MBR will be replaced with a shiny new one, and you should then be able to boot your system normally. In some cases, you may need to repair the boot sector in addition to the MBR. If your system still doesn't boot properly, repeat the steps above, but issue the fixboot command instead.

NOTE: These procedures assume that you have only one operating system installed. If you are an advanced user and have a multi-boot system with more than one operating system, you may need to do some additional reading about the fixmbr and fixboot commands at the Microsoft website.

Do you have experience with a damaged master boot record? Post your comments below...

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Posted by Bob Rankin on June 7, 2006 08:59 PM


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Related Keywords: Windows   mbr   master boot record   boot sector   fixmbr  

Most recent comments on "Fix MBR"

(See all 100 comments for this article.)

Posted by:

Rufus
08 Feb 2010

"Seems like it can't hurt..." NO NO NO. It CAN bloody well hurt. FIXMBR is vile because it will destroy partition information and effectively wipe the C drive (which is usually the one with the MBR) clean and you will lose all your files and programs. DONT USE IT UNLESS YOU BUY ANOTHER HDD - COPY YOUR FILES TO IT FROM THE RECOVERY CONSOLE - (EASIER SAID THAN DONE) AND THEN FIXMBR, followed by FORMAT followed by a clean install. 1 days' worth of fun which, if you are not too careful, will cost you your files.

EDITOR'S NOTE: It's extreme to say that FIXMBR *will* destroy your partitions. In some rare cases, it may. But that sure isn't the norm.


Posted by:

Rufus is an Idiot
23 Feb 2010

Rufus you are an IDIOT and clearly un-informed!.

fixmbr does not remove all your freeking file doos - f%$#$!@ing learn more about a commands before commenting next time - idiot!


Posted by:

BlueRaja
27 Feb 2010

@Rufus: The master boot record is not "on the C:\ drive;" it does not belong to any mapped partition. If anything, it "belongs" to the hard-drive itself (sector #0, to be specific)


Posted by:

MHess
02 Apr 2010

@Rufus

fixmbr does not wipe your files, but formatting clearly will. Follow the advice in the article. Obviously, it's always a good idea to have a backup.


Posted by:

Jaimidog
04 Apr 2010

I desperately need help!!!

Two days ago Microsoft started the automatic updates. A box came up saying that the computer would restart in 8 minutes and gave me the option to Restart Now or Restart Later. I chose Restart Later. I went to bed & when I got up the next morning the computer was froze on the Windows is shutting down screen. I had to turn off with the switch. When I turned back on, the computer won't start and gives the error "Disk Boot Failure, insert system disk and press enter. At the top of the screen it states:

Diskette Drive B: None
Pri. Master Disk: None
Pri. Slave Disk: None
Sec. Master Disk: CD-ROM, UDMA 2
Sec. Slave Disk: CD-ROM, UDMA 2

In BIOS at the Main Screen it shows:

Primary Master [AUTO] (My only other option is NONE)
Primary Slave: [AUTO] (My only other option is NONE)
Secondary Master: [MATSHITADVD-ROM SR-8588]
Secondary Slave: [_NEC CD-RW NR-9100A]

On the BOOT Screen it shows:

1. IDE Hard Drive [None}
2. ATAPI CD-ROM [MATSHITADVD-ROM SR-8588]
3. Removable Device [Legacy Floppy]
4. Other Bootable Device [Disabled]
Silent Boot [Enabled]

I don’t know why the above sees my floppy drive as “B”. It was “A” prior to this problem. Or at least showed “A” in Windpws Exployer.

I have a second hard drive in this computer and they are connected with the same cable. I thought maybe the cable went bad so I changed it out but didn't help. The master and slave/cable select switches have not been changed since the second drive was put 5 years ago. It appears that the computer cannot find either hard drive so would it be logical to think that it’s not a bad hard drive but something else?

I have a Sony Vaio PCV-RX850 and do have the Recovery CD's that came with the computer. I'm afraid to use them without trying something else first. I have some important files that I really need to try and keep if at all possible. I have done a lot of reading on the internet where there have been several suggestions but I don’t know what to try first since none of the problems were exactly like mine.

I will gladly kiss the feet of the one(s) that can save my data!!


Posted by:

Debbie
05 May 2010

Hi, I had the blue screen issue with "unmountable boot volume. I put in the windows xp disc, pressed f12 to boot from dvd, the files loaded and now my screen is light blue. The screen is light blue and looks like the normal screen that you would choose which user you are to start windows. I have done this twice and this is as far as I can get. If I turn the computer off I will then go back to the blue "unmountable boot volume" screen. Can you please help? Thanks.


Posted by:

Bill
03 Jun 2010

When my system boots it show my Maxtor hard drive size is 0 Meg. The system was run and it locked up. After a system restart it asked for a system disk. After another restart is when the system no longer recognized a hard drive. The drive is spinning and a old drive does work in the computer which eliminates other computer hardware. With out a hard drive being recognized I am have trouble booting Windows XP system disk. What would you suggest? I am electronically inclined. I was thinking off trying a new hard drive control board from a exact duplicate drive.


Posted by:

dalvin
08 Jun 2010

me juz installed norton goback on my computer
adn it say never install any parttion software
but i go installed linux OS when i log in computer it say bla bla bla error driver file goback.sys
norton go back is a good utilities start with the boot to restore driver depanding on ur HDD size


Posted by:

ess
08 Jun 2010

tried all of these, problem could also be bad hard drive. i ran a HDD read test on my problem machine to find out the hard drive itself is bad


Posted by:

Norbert
12 Jun 2010

I used the recovery console to create a new hard drive as follows:
diskpart
list disk
select disk 0
clean all (was taking two long so I stooped it and started over with out it)
create partition primary
select partition 1
Format fs=ntfs
active
exit

Then I put in Win XP Pro and my programs

NO MBR

I was able to bring up the system with a floppy disk
The system worked great BUT
The main partition was up against the first track of the HD!
No master boot record?

What command did I leave out of the recovery console?

I could move the entire partition 1 GB down,
Than what is the best way to add the MBR?


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Article information: AskBobRankin -- Fix MBR (Posted: June 7, 2006 08:59 PM)
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