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Windows 7: Accidentally installed XP Pro on my Win 7 machine

11 May 2012   #1

Win7 x64
Accidentally installed XP Pro on my Win 7 machine

I have an HP with a 1.5TB WD drive in it. I had attached a USB cabinet with a 160GB drive to install XP on. I booted XP install disk from the CD, formatted the 160GB drive and began installing the OS files. The phone rang, I walked away, and I came back to a machine that is just trying to boot XPP instead of Win7. I am not sure what happened. At first a message said to choose your OS, and it showed 2 instances of XPP and then immediately rolled to an error saying there is a hardware configuration error. I went into the HP recovery tool (win7 x64) and ran the auto-fix startup tool several times with no successful message. Now when it boots, it simply says. BOOTMGR not found. I have gone into command prompt and browsed to my files, and the user data is all intact so I think that XPP has overwritten and/or reconfigured my boot partition data. I am certain that someone else has encountered this error before so can you point to a forum link or provide me with some instructions to help sort this out? I am fairly competent but I don't like poking in the partitions without clear instructions. I cannot lose the data on this hard drive because there is no chance of me getting another hard drive to back it up for a few weeks. Thanks in advance for your assistance.

My System SpecsSystem Spec
11 May 2012   #2
Microsoft MVP


Is WIn7 HD set first HD to boot in BIOS setup? Do that now and then try booting 7 again. If 7 won't boot power down to unplug all other HD's and try again.

This is why you should always unplug any other HD while installing another OS.

You said you formatted the 160gb HD so it's possible it only stole Win7 boot as XP will always do when installed after Win7 to the same HD or if the other HD is incorrectly left plugged in.

Try unplugging all other HD's, set Win7 HD first to boot in BIOS setup, boot the Win7 DVD or System Repair Disk to access System Recovery Options then from a Command Prompt mark the Win7 partition or it's 100mb System Reserved partition Active. Close Command Box, return to Recovery Options to run Startup Repair - Run 3 Separate Times until Win7 starts.

You can download the latest official Win7 installer ISO with SP1 for your licensed version and burn to DVD or write to flash stick using the tool given in the steps to Clean Reinstall - Factory OEM Windows 7.

Once Win7 starts you can plug back in the XP HD and boot it by tapping the HP ESC key at boot. If you don't like this method of booting via BIOS, add XP to a Windows Dual Boot Menu using EasyBCD (free Download at bottom of page - no name or email required)

My System SpecsSystem Spec
11 May 2012   #3

Win7 x64

Thanks GR, I will try this in the morning and let you know. I appreciate your time.
My System SpecsSystem Spec

11 May 2012   #4

Win7 x64

Quote   Quote: Originally Posted by TechnoTarzan View Post
Thanks GR, I will try this in the morning and let you know. I appreciate your time.
Verified only drive in system
100MB Partition marked active
Ran Startup Repair 3x, though each "completion" forced a reboot to try the subsequent time

ProblemEventName: StartupRepairOffline
Signature 0/1: 6.1.7600.16385 (OS version mismatch?)
signature 03 - unknown
signature 04 -1
signature 05 SystemDisk
signature 06 1
Signature 07 CorruptBootSectorCode
OS Version: 6.1.7600.
Locale ID 1033

Any suggestions next? I have an original Home Premium x64 and a Win7 Ultimate x64 disk as well. The unit came with HP x64 and I did an anytime upgrade to Ultimate. Is this why the xp ultimate usb key says it cannot repair this version of OS? Maybe I should make a HP x64 boot key?
My System SpecsSystem Spec
12 May 2012   #5

Win7 x64

After doing all of the above 2x, the system still boots to the original screen with the two instances of XP Pro and then immediately errors out with error screen:

Windows could not start due to computer disk hardware configuration problem
Could not read from the selected boot disk (locked?) Check boot path and disk hardware.
please check docs about hdwe disk configs etc etc...

True that on the disconnect ALL drives. Totally spaced on that, I know better.
My System SpecsSystem Spec
12 May 2012   #6

Windows 7 Pro 64 bit SP1

you probably hosed your MBR. Windows 7 uses different MBR than XP does. Do you have another computer? You can take your internal HD out and use your USB enclosure to mount it to another computer. From that computer you can download EasyBCD program and install new MBR along with new entries into the bootloader. The easybcd program will allow you to load a bcd off of an external device which is good.

This would probably be easiest way to recover otherwise you'd have to startup with the Win 7 recovery environment and manually do all this with the bcdedit command.
My System SpecsSystem Spec
12 May 2012   #7

MS Windows 7 Ultimate SP1 64-bit


Do you have a System Repair Disc? Yes/no

do you have a Win 7 DVD? yes/no
My System SpecsSystem Spec
12 May 2012   #8

Win7 x64

Do I have another computer: xp laptop and iMac.
I have the original HP System RESTORE Disks, not a system REPAIR disk, and yes I have Win 7 DVDs.

The PC I had a couple years back had a Dual Boot dual drive using BCD with XP and Vista on them. I can download it and take a poke in there at the editor. Not afraid of CLI. Thanks again.


So I went quickly to refresh my BCD history and remembered I had a copy on a USB key, but actually found these two commands so I gave them a kick and VOILA! Back to normal -
bootrec.exe /fixmbr bootsect.exe /nt60 all /force CASE CLOSED. :)

FYI - I am in Costa Rica, in the jungle 250 yards from the Pacific. Next time any of you want to get out and chill or surf some really good waves. Drop me a line at

My System SpecsSystem Spec
12 May 2012   #9
Microsoft MVP


Sorry, just caught up with this thread. Seems bootrec tool helped solve this.

It is included in Troubleshooting Windows 7 Failure to Boot which would have been the next step if Win7 didn't repair using normal Dual Boot troubleshooting steps. You might want to bookmark it.

Enjoy those waves. I hope to come to Costa Rica some day!
My System SpecsSystem Spec

 Accidentally installed XP Pro on my Win 7 machine

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