Fix MBR
"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?

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:
- Restart your computer with the Windows XP Setup disk in the CDROM drive.
- 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.
- After a few minutes, you'll see a prompt to press the R key to start the Recovery Console.
- 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.
- Enter your Administrator password. If you don't enter the correct password, you cannot continue.
- 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...
Posted by Bob Rankin on June 7, 2006 08:59 PM
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Most recent comments on "Fix MBR"
(See all 78 comments for this article.)|
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Hello Bob! Thanks for the great article. I hope you can help me with a follow up question. (I have a RAW file system problem and I'm pretty sure I have boot sector corruption) Does fixing the MBR or Boot Sector using this technique compromise data on the rest of the disk? I have important data on my drive that I would like to recover and I want to know if I'll still be able to retrieve it using data recovery software after replacing the MBR. My plan was to retrieve as much data as possible, (using data recovery software) and then simply reformat the disk after I had recovered all the important bits. However, if I could get the disk running again simply by replacing the MBR using your guidelines I could save money by not having to purchase data recovery software. Would you advise trying to recover all important files using data recovery software prior to replacing the MBR? EDITOR'S NOTE: When the MBR is damaged, the system may report that you have a RAW file system, even though your data is still all there. My best guess is that fixing the MBR will bring the disk back to life, but it's hard to say for sure. I *think* the TESTDISK program can make a temporary fix to the disk, and then let you decide how to proceed. |
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I am running Win XP Pro. I have two hard drives on my system. One is my primary (main HD) disk I use for 'everything'. The second disk I use to backup everything from my primary disk (on a nightly basis). EDITOR'S NOTE: That might work, but what error/problem do you see when you try to boot from the primary HD? |
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Good Article Bob. A few days ago, My system displays "Error loading operating system" on the screen. When I try to access windows drive (C:) in Recovery Console through XP CD, it said Invalid Drive. But I Can access other drives (D and E). When I try to install fresh XP, it displays the C drive as unformatted drive. But others in correct size and space with label name. After, I format the C to install XP. If I try fixing the MBR or Boot Sector that can helped me? EDITOR'S NOTE: YES! That's probably what the problem is. Fix the MBR, and your disk may spring back to life. |
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Hi Bob, just found your article - this is my problem: Gateway GT4010 PC (AMD64 Processor 3500+ w/WinXP media ctr ed 2005, 2.2GHz 512 Kb cache, (1024mb DDR) \, West Dig 200gB HDD (7200rpm w2MB cache). EDITOR'S NOTE: I sure try the MBR fix before spending a lot of money on a data recovery service. Look for the TESTDISK program. |
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After trying EVERYTHING I knew of and referring to sites such as this one for possibly something I might have missed I finally figured out that all this machine wanted was to have a shiny new partition made for the new install. At the prompt where it displays the HD's, I clicked on the option to delete the existing partition, which was the C:/ drive, had setup re-partition the drive and then did a quick format to the NTFS format and had setup finish it's thing and ta-da, it finally worked so that Windows could complete the setup process. Hope this helps someone out there who is having as much trouble trying to simply re-install Windows. Peace! |
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Hello - I'm very happy to find this article - it sheds a little light on my situation. I hope you can help me with a perplexing issue, on to TESTDISK....the Analysis lists the first partition [NTFS] twice which which according to the testdisk wiki "points to a corrupted partition or an invalid partition table entry" proceeding to the next step with TestDisk "Quick Search" it only Lists the IBM service recovery partition - no more mention of the main NTFS partition. "deeper search" produces the same result... I can only see the 5gb recovery partition. What can I do? I believe the MBR is messed up and i have corrupted boot sectors. any advice? I desperately would like to recover the data on my main NTFS partition. |
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Hi! |
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I'm having a problem getting my Admin password to work - presume it's the one I log into Windows with? At any rate I tried it twice plus also the one for the alternate Windows version on another drive, but neither were accepted. Finally I tried none at all, but that just bumped me out completely - could you perhaps clarify on what to do in such a situation? EDITOR'S NOTE: This should help: http://www.askvg.com/how-to-reset-recover-forgotten-windows-nt-2000-xp-2003-administrator-password/ |
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I used the command fixboot and I have solved my boot problem on XP |
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Hi, Since I can't access my hard drive on the laptop and the DVD how can I solve it up? |
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