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?

Got a Damaged 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

master boot record

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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Most recent comments on "Fix MBR"

(See all 119 comments for this article.)

Posted by:

12 Jun 2010

I used the recovery console to create a new hard drive as follows:
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

Then I put in Win XP Pro and my programs


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?

Posted by:

06 Oct 2010

Hi, I was working on my laptop (Windows XP SP3)today morning and suddenly it hung and started showing HP boot screen..but did not.Then it popped MBR error with rest of the screen blank.

I tried using my old recovery console disk (this has XP SP2, I did not create recovery disk after I upgraded to SP3) to repair the damaged MBR file, but I get "hard disk write error" and asks me to quit setup.

Assuming that there was a problem with the boot CD unable to recognize the HDD, I used a stand alone XP SP2 cd and pressed F6 to install 3rd party drivers. Still it did not work.Is it possible that I connect my HDD to other computer and take a back up first and then reinstall XP from scratch? I am worried about my data. Please advice me.

EDITOR'S NOTE: Yes, connect the drive to another computer via USB (get an enclosure kit) and you can do what you've proposed.

Posted by:

07 Oct 2010

Thank you for the response. I did try doing what I mentioned in my previous post. The problem is that when I connect the HDD to other computer, it gets recognized as a mass storage device but does not show up on my computer to open it!! :(

When I tried looking it up through device manager, the drive is shown as unallocated drive which needs to be initialized. What does that mean? and if I do initialize it..does that harm the drive by ruining the partition and losing the data in partition permanently? Please advise..

Posted by:

18 Oct 2010

I will use Hirens Boot Disk. It will help you to solve any problem with your HardDisk Drive. It quiet simple to work with Hirens Boot Disk.

Posted by:

05 Nov 2010

I'm runnung a Windows XP Pro box. Today it says NTLDR IS MISSING on bootup. I tried running recovery from my XP disk, and tried FIXBOOT.
Nothing works. Any suggestions?

Posted by:

07 Nov 2010

I was trying to install WinXP to a USB 2.0 external HD from my Dell laptop using a CD installation disk. After copying the files to the external HD it was going to restart the laptop. I removed the installation CD while the laptop was starting to boot and then I get an error message "could not start because of a computer disk hardware configuration problem. Could not read from the selected boot disk. Check boot path and disk hardware." I disconnected the external HD from the laptop and restarted it but it also gave me the same error message.I used the recovery console from the installation CD and tried the fixmbr and fixboot commands but it still gives me the same error message. Any ideas?

Posted by:

29 Nov 2010

Fixed the MBR many, many times. Well the XP Recovery Disk hangs at the "repair" or "re-install" or "quit" screen. Re-booted like 100 times freezes at that screen every time no key does anything. Any suggestions?

Posted by:

18 Jan 2011

i tried to fix mbr using recovery console and it said that it fixed but on rebooting again black screen comes.
please help me out

Posted by:

Marc Hall
01 Feb 2011

What if the HDD is connected via USB?

Posted by:

02 Feb 2011

What do you do when you have a black screen???

Posted by:

17 May 2011

worked like butter! Thanks so saved me a bunch of heartache.

Posted by:

24 Jun 2011

Why do both you and Ask Leo keep mentioning a windows CD/DVD? All people gerare a recovery partition and have to burn a recovery disk. My house went through 4 computers aand none of them came with a real windows disk. Nobody bought windows, either

Posted by:

26 Jun 2011

I am trying to get to the repair screen, I have the blue screen that comes up with unmountable Boot volume. When the system boots up it acts like it is loading Windows xp but then the blue screen comes up everytime. I am hitting, f12, f8, none of these options is helping. I dont see the repair screen at all. I am also trying to reboot with the disk and the same thing comes up as well, there is no repair option or the dos format to have me enter in the codes suggested. chkdsk/r or fixboot. Does this mean my Hard Drive is not able to be fixed? again there is no option at all for repair option at all while loading the XP disk. Thanks for your suggestions.

Posted by:

22 Sep 2011

have dual boot system, one for xp the other for vista, with xp is the primary boot.

Lately, I installed the power quest; partition resizer on the vista to extend the size, no complaint about the installation.

But, when I started the pqpr, a shot pop-up message asked me to correct the conflict in the vista partition.

I pressed y, and restarted the system, so far, the blue screen complained with proposing to use chkdsk /f to resolve the problem.

I then used "PTTD partition table doctor" to solve which reported the total sectors of 68356538,
with actual sectors of 68356575, the difference of the last 2 digits. The PTTD does nothing to solve the overlapping partition.

In xp which is still bootable, can see the vista as another drive.

Your help please!!!

BTW: Is it posible to copy patition table from xp to vista?, as xp works well, but vista has problem of partition size incorrect.

Posted by:

02 Nov 2011

If you are stuck with the XP Password bug, (like I was) just use a Windows 98 CD or DOS boot disk. Once you boot to DOS, use


Remove the CD or floppy, reboot and see XP resurrected! :)

Posted by:

15 Nov 2011


Great suggestion and a save I've used lots of times Willie!

If you don't have a copy of the venerable but still hugely useful DOS operating system available get one from
Load it on a flash drive or ISO copy to a CD; if necessary, adjust your BIOS to boot from that media first, and Away You Go!

One caveat, if you are running a dual or multi-boot system and are using an alternative boot loader such as GRUB you will have some additional jiggery-pokery to do, but you already know how to do that!

Posted by:

05 Mar 2012

I tried all the suggestions. nothing worked. I'm ready to punt and go Apple. Put all this Microsoft nonsense, BS, headaches, insanity, frustrations, ridiculous crap behind me forever. Even when things are working correctly, its so slow and non intuitive, why do we put up with this crap?!?! because it's cheaper - get what you pay for. I'm out of here!!!

Posted by:

10 Apr 2012

How do you do the master boot record make more than 4 partitions?

Posted by:

E Bat
05 Jun 2012

I am a recent convert to a Free software called MiniTool Partition Wizard - once I figured out a few bugs/tricks, it surprises me by doing more than I expected, rather than the usual less.
Hidden in the partitioning choices is an embarrassingly simple button, "rebuild MBR", only an option when a whole drive, rather than partition, is selected. An unbootable drive with partitions invisible to XP's Disk Management was fixed in 30 seconds.
I used MiniTool to clone/ image a 5-partition IDE HDD on an older Dell 4600 to a new SATA drive; first few false starts involved missing key matters, i.e. do NOT reboot with old drive still in place. This software even allows one to change the partition ID, so I first used that feature to just find the original IDs from the old drive, then entered the same numbers for each new partition. Finally, I ran the convenient "rebuild MBR" feature last. With a couple reboots, the entire drive appears to be running fine, even allowing Windows update to function. This may be of greater concern for OEM systems like mine, where Windows is happier if it believes the hard drive has not changed.
NOTE, however, that a slow HDD appears to be related to the "write behind caching" setting. Once I allowed that the drive speed jumped to the expected 40-55MBs both read and write.
A huge plus for me is it all ran without uninstalling my trusty GoBack (although I did Disable it while running disk intensive activities I knew would render it inactive anyway). Norton Partition Magic refuses to run with GoBack installed even if you're only making changes on hard drives other than your primary one.
If you are trying to copy your active primary partition, MiniTool will prompt to allow completion of tasks during a re-boot. None of the changes made, including fixing MBR, re-sizing NTFS partitions, copying original Dell restore or utility partitions as FAT, FAT32 required any external input from CD or other source.
I already was running a parallel backup HDD, so had very redundant backups in case disaster struck. That HDD was an earlier clone made with XXClone, which was very easy and well-explained except that the free version will only copy a single partition, to an entire second drive, and one of them must be running as your primary drive.
With some practice (and safely redundant backups) the MiniTool will allow advanced tasks like adding/removing partitions, resizing and copying or deleting, all automated in a sequence that initiates after you finish the list. Each task will not be accepted if it violates rules or processes, so the entire run is quite well-protected.
The one peculiar issue I had at first was my XXClone HDD worked fine, only if the original drive was present. I think the issue related to the GoBack partition, absent on the second drive. The system was finding it, as drive D, on the original drive, but losing it when that drive was missing at startup. Drive letter issues can quickly create major screw-ups when several multi-partitioned drives exist, especially if programs are installed on more than one and are looking for dlls or documents or what-have-you.

Posted by:

22 Aug 2012

Followed your fixboot and fixmbr instructions, worked first time, (and second time next day!) but I am still waiting for the thunder - should I disconnect my PC in case it is fried by lightning?
Thank you Bob

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Article information: AskBobRankin -- Fix MBR (Posted: 7 Jun 2006)
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