How do I replace orginal MBR in Win 7?

mbmalone · 27 Jul 2009

It appears they have changed things from the old way, which worked fine.

SIW2 · 27 Jul 2009

Hi,

What are you trying to do exactly?

What error makes you want to replace the mbr , and what have you tried that hasn't worked?

mbmalone · 28 Jul 2009

I've been messing with dual boot setups. I know how to do it, but I was trying to do it the easiest way possible. It used to be you could just boot with the original CD and choose repair, but it doesn't seem to work anymore. I heard they changed things with Win7 to make it more difficult.

chuckr · 28 Jul 2009

mbmalone said:

I've been messing with dual boot setups. I know how to do it, but I was trying to do it the easiest way possible. It used to be you could just boot with the original CD and choose repair, but it doesn't seem to work anymore. I heard they changed things with Win7 to make it more difficult.

First of all, you wrote:
How do I replace orginal MBR in Win 7?

I'm assuming what you mean is:
How do I restore the original (XP) MBR, using Win 7?

If you know what you're doing, and you're referring to Win XP (only), not Vista/W7
try this (The "manual" way):
Last worked OK for me with Build 7201.

Boot from your install DVD to get Win7 code running.
At: English_US keyboard, click 'Next'...

Hit: Shift F10 to get an Admin Command Prompt.
( Now you have to find out the 'letter' of your DVD: )
type: diskpart
then: list volume -- Note the letter of DVD (D:?) and boot HDD (C:?)
type: EXIT to get out of 'diskpart' and back to the cmd prompt.

type: D: (? for your DVD letter)

type: CD boot
type: bootsect /nt52 C: /mbr (C:? for your boot HDD)...
--- He should say "Success" ---

type: EXIT to get out of 'Command Prompt' and back to Win7 Setup.

That ought to do it. Cancel out of Setup, reboot and you're home.
-----------------------

Bootsect.exe updates the master boot code (BS) for hard disk partitions
in order to switch between BOOTMGR and NTLDR.
You can use this tool to restore the Boot_Sector (BS) on your computer.

/nt52 Applies the master boot code (BS) that is *compatible* with NTLDR to SYS,
ALL, or <DriveLetter>. The operating system installed on SYS, ALL, or
<DriveLetter> must be older than Windows Vista.

/mbr Updates the Master Boot Record (MBR) without changing the Partition_table
on sector 0 of the disk that contains the partition specified by SYS, ALL,
or drive letter.

When used with /nt52 option, the Master Boot Record (MBR)
is *compatible* with operating systems older (XP) than Windows Vista.

When used with the /nt60 option, the Master Boot Record (MBR) is
*compatible* with Windows Vista, Windows Server 2008 or later.

curtranhome · 29 Dec 2011

SIW2 said:

Hi,

What are you trying to do exactly?

What error makes you want to replace the mbr , and what have you tried that hasn't worked?

The MBR could be infected by viruses and other malware to cause corruption with in the file which, in turn, causes your computer to stop booting correctly even though the installation of the OS is correct. To answer your second question, the MBR can not be replaced by the user within the desktop. You will get an 'Access Denied' when trying to replace it with a working one. I have tried all of this when trying to restore a friend's computer without doing a system restore. BUT, if you insert the install disk for the OS on the drive (without booting from the disk), the computer will automatically use the correct MBR on the disk (unless it to is corrupted) and then boot to the installed OS on the drive. I hope this helps you as well as others reading in to this! :)

pallesenw · 29 Dec 2011

It is possible to overwrite the MBR from within Windows, but if you are infected with a rootkit, you can never know for sure, if it just makes you believe that you have overwritten it.

mjf · 30 Dec 2011

I'm not that knowledgeable in malware protection. But a "virus" or a dual boot (linux) configuration can play around with your MBR. Basically the MBR contains the boot code the BIOS hands off to and the HDD's partition table.

You can try the following:
Option 1-
Boot a system repair CD (you make from "Backup & Restore") and run the automatic repair function up to 3 times.
Option 2-
Boot a system repair CD and go to the command prompt option and type
>diskpart
>bootrec /fixmbr
..........you can try stopping here and see if your problem is fixed or continue with
>bootrec /fixboot
>bootrec /rebuildbcd
>exit
then
Reboot

This sequence of operations rebuilds your full boot sequence for Windows 7.

When thing are running smoothly I suggest you backup your MBR with this little utility. You can then manually replace it if either your MBR boot code gets infected or your partition table gets damaged.
MBR Backup - Back up your Master Boot Record (Freeware)

SIW2 · 30 Dec 2011

Huh?

How does that answer why the op thought his particular issue was due to a problem with the disk code.

People often assume any boot problems are caused by damage to the mbr.

While it is not impossible, it is unlikely.

Most boot problems are caused further down the chain.

curtranhome said:

SIW2 said:

Hi,

What are you trying to do exactly?

What error makes you want to replace the mbr , and what have you tried that hasn't worked?

The MBR could be infected by viruses and other malware to cause corruption with in the file which, in turn, causes your computer to stop booting correctly even though the installation of the OS is correct. To answer your second question, the MBR can not be replaced by the user within the desktop. You will get an 'Access Denied' when trying to replace it with a working one. I have tried all of this when trying to restore a friend's computer without doing a system restore. BUT, if you insert the install disk for the OS on the drive (without booting from the disk), the computer will automatically use the correct MBR on the disk (unless it to is corrupted) and then boot to the installed OS on the drive. I hope this helps you as well as others reading in to this! :)

mjf · 30 Dec 2011

I'm not sure you is responding to whom.
The original post was in 2009!!
I was following up based on curtanhome resurrecting it and others may now stumble on the thread.
I attempted to answer the old original OP question
"How do I replace orginal MBR in Win 7?"
and what to do if the problem is further down the boot chain.

mjf · 30 Dec 2011

The automated method was given as my option 1. From first hand personal experience the automated system repair does not always work. If your problem is related to the boot sequence the bootrec command was introduced in Vista then Windows 7 specifically to address these issues. I have found this to work when the automated repair did not - just sharing my experience.

I think bootsect is focused on the NTLDR boot loader and more applicable to XP or XP dual boot environments.