Solved Reverse dual-boot setup.

[johnnya]

Good day all.

I would like to reverse the dual-boot capability I set up on my test machine.
The original machine is Windows XP SP3. I loaded Windows 7 Home Premium on partition D.
When the machine now boots, I am given the option of Windows 7 or Older version of Windows which is of course Windows XP. Works great. Now I would like to remove the Win 7 installation and have it boot straight to Windows XP as before. Not exactly sure how to do this.
Don't want to render the machine unbootable or maybe mess up the MBR.
Many thanks gang.
Cheers
JohnnyA

 

[FliGi7]

Which drive is your boot drive now? If you originally had XP on C: and loaded Win 7 on D: and put the boot partition there, it could be as simple as just making C: the first boot drive now. If, however, you loaded Win 7 onto D: and put the boot partition on C:, then you can fix it with the following:

1) Disconnect the D: drive
2) boot from the Windows XP cd
3) At the setup screen press R to enter the recovery console for your C: drive
4) At the command prompt type "fixmbr" and hit enter, then type "fixboot" and hit enter
5) Type "exit" and the system will restart, hopefully, into Windows XP

 

[johnnya]

Thanks for the speedy reply FliGi7. Sorry I forgot to mention that I only have 1 HD with two partitions C: & D: so I cannot unplug drive D: Also want to get rid of all traces of Win 7 files/folders but not sure what to delete.
Thanks again
JohnnyA

 

[FliGi7]

Once you repair the MBR on the drive with the XP recovery console. You can boot into windows, open My Computer, and format the D: partition. Everything will be gone. Or, you can go to device manager, delete the D: partition with Win 7 and extend the C: partition to fill the whole drive.

 

[johnnya]

Can't thank you enough FliGi7. Currently doing a full drive image with Macrium and will perform your fix when it is done. You have been a big help.
Cheers
JohnnyA

 

[unifex]

Actually, if you have only one hard drive, then you don't need to do anything drastic. Your MBR is not broken, so there is no need to repair it.

Just open msconfig, go to the boot tab, and delete the line with the OS you want to delete. After that reboot and make sure you're booting OK into the OS you want. Once done you can safely get rid of the other OS.

 

[FliGi7]

Actually, if you have only one hard drive, then you don't need to do anything drastic. Your MBR is not broken, so there is no need to repair it.

Just open msconfig, go to the boot tab, and delete the line with the OS you want to delete. After that reboot and make sure you're booting OK into the OS you want. Once done you can safely get rid of the other OS.

I've done this before and it hasn't worked for me. Don't ask me why or how, but I just don't recommend it after it happening to me. In theory, it should work, but doing the fixmbr and fixboot seems just as straight forward and leaves little room for error.

 

[unifex]

It has certainly worked for me.

Basically, even if you just erase one OS without doing anything else, MBR would not know it. It will still give you an option to boot to two OS. And then of course if you choose the deleted OS, then you get a black screen. Removing the line from msconfig removes this choice, that's all it does.

As an example, I have an old desktop and there still is an option to boot Windows ME, which is long gone. But I never bothered to do anything with the MBR. The other OS, Win2000 does not know about the existence or non-existence of the former.

 

[unifex]

Actually, even on my main machine, where I have each OS on it's own hard drive, the situation is the same. I had Vista originally and then I added another hard drive with 7. Then something broke down, not sure what, but the machine refused to boot. I plugged each drive individually, ran Start-up Repair, so now each drive can boot on its own.

But then I added a SSD, put another copy of 7 on it. The trick is, the SSD is configured to use AHCI (or RAID on my Dell), while the older HDDs were IDE. So now each time I boot up, I have an option to choose an OS, but half of the OSs won't boot anyway due to the wrong BIOS settings. But, the OS with the right BIOS settings boots just fine, it has no way of knowing about the others.

 

[johnnya]

Always such a good learning experience at the forum. Great advice from you both.
I am grateful for your help.
Cheers
JohnnyA

 

[SIW2]

The mbr has nothing to do with it.

Easiest way is :

Put win 7 dvd in dvd drive, press windows key + r to open run dialog and type in

z:\Boot\Bootsect.exe /nt52 ALL /force (replace z with dvd drive letter )

Then boot into XP and delete win7 partition.

 

[johnnya]

Thanks SIW2. Last question - what os work I be in when I try your suggestion?
XP or W7
Regards
JohnnyA

 

[SIW2]

Win 7 or XP - probably better from XP as that was the first installed o/s.

It may tell you the update may be unreliable - that's normal.

 

[FliGi7]

The mbr has nothing to do with it.

Easiest way is :

Put win 7 dvd in dvd drive, press windows key + r to open run dialog and type in

z:\Boot\Bootsect.exe /nt52 ALL /force (replace z with dvd drive letter )

Then boot into XP and delete win7 partition.

The MBR does have something to do with it...

http://technet.microsoft.com/en-us/magazine/ee851681.aspx

I would still recommend a fixmbr prior to fixing the boot record, as stated, but that's just me.

 

[SIW2]

That post is wrong.

 

[FliGi7]

Ok, then. Assuming that article from Microsoft's Technet is wrong (which you should contact them about in all seriousness if it is wrong), then why does the Linux GRUB bootloader (which writes itself to the MBR) get wiped out after installing Windows if the Windows bootloader doesn't have anything to do with the MBR?

 

[SIW2]

LOL.

If you let grub install itself to the mbr - it automatically takes over the boot management.

Clearly you have to remove that if you want to use windows boot manager.

Grub is not involved in this case ( unless I missed something in the thread ).

Yes the Technet post is definitely wrong - it's not the first time.

Vista/7 disk code has no problem loading nt52 bootcode and vice versa.

Vista/7 disk code contains extra code relating to bitlocker - if you are not using bitlocker - it doesn't matter.

 

[FliGi7]

LOL at what? You missed the point entirely, actually. Re-read what I wrote. The point was the re-installation of GRUB after installing Windows. If the Windows bootloader does not, in fact, touch the MBR as you say, then why is the MBR overwritten to the point of removing GRUB when you install Windows after Linux?

Instead of letting this go on, I will answer and say it does, in fact, rewrite the MBR when Windows is installed, based on the OS version (XP has its own as does Vista/7). So, the MBR does have something to do with the bootloader which is the problem here, contrary to what you stated in your original post. That's the whole point, which was somehow hard to arrive at. This backs up my opinion that I would run a fixmbr to write the XP MBR back to disk rather than leaving the Vista/7 MBR. It may or may not have any effect if both MBRs are cross-compatible with each others boot section. Whether you agree or not is separate.

 

[SIW2]

Windows will always write the mbr code during install - you may not have a valid one already - or you may have something else on there - e.g. grub, so it is default during install.

LOL was at the article - looks like a typo - if it said pbr, or vbr that would make some sense.

The command given in the article you linked to does not affect the mbr.

If for some reason - you do want to rewrite the mbr code as well ( e.g. to get rid of Grub ) - use the /mbr switch, like this:

d:\boot\ bootsect.exe /nt60 all /mbr

You notice he doesn't do that in the article - because there is no need to rewrite the mbr code.

However, it is just a tiny bit of code and won't do any harm if you include it.

 

[johnnya]

Well here I am still in the Fox Hole watching the shelling going back and forth over my head and thinking "What was I thinking when I signed up for this"
Oh well, here I am all dressed in my Bomb Disposal outfit with wire cutters in hand - now which one - the Red wire or the Green wire? Hell just pick one, what can go wrong.
Ok lets go with Red. Oops, wrong one- shoot. BOOM!!! lol

I think I will take a break, reread all the suggestions again in the morning and then make a decision on what to do. Thanks for all the help folks.
Cheers
JohnnyA