I'm having quite a bit of a big issue downgrading my PC from the Win8 CP back to Windows 7.
I started by zeroing the HDD in my computer, like I normally would when installing a fresh OS install.
Everything went well, until I popped my Win7 install disk in the drive and went to install.
The install went smoothly until around 10-15% on "Expanding Files" (Not sure exactly where things went awry, I left the PC unattended for a few minutes).
I came back and noticed an error was being displayed on my screen. It said that Windows was unable to install due to a missing or corrupted file. I know that there is nothing wrong with the disk, because I have used it many times before, and there is not one single scratch on it.
Upon restarting my PC without the disk in it, it shows this message "BOOTMGR is missing Press Crtl+Alt+Del to restart.

I am in great need of help, seeing as it is my only PC that this happened to, and I had to use someone else's to post this.

- Duster

Try these

http://answers.microsoft.com/en-us/wind ... 8f7a0a9720

Well, using a DVD that was properly installed several times might not mean it will always work OK. Besides the DVD drive may also not recognize self-burnt disks sometimes.

FYI I burnt a DVD with an external recorder, and it read the disk quite perfectly in the early. Unfortunately some days later when I returned to it with the burnt Windows 7 DVD it encountered the same problem, saying that the files were corrupted, and after that I found that the drive didn't read burnt DVDs at all.

So, what I mean is, when this problem:

happens, sometimes it's just because the disk is damaged. This usually not happens if you are using a Windows installation DVD in retail FPP, as it is well-manufactured DVD-ROM.

However, if you are using burnt disks, there's also a circumstance that the drive not being able to read the disk. You can insert some other burnt DVDs to see whether they can be read later. If it really cannot read burnt DVDs, you may also use a USB stick for alternative.

Clean the disk and try again is my first recommendation.

Try making a bootable USB stick with this

http://www.microsoftstore.com/store/mss ... vd_dwnTool

Clean the DVD drive laser too

Try the very same disc in a virtual machine. It works? Then try to reset BIOS settings on your host and try again.

Yep I would advise doing so maybe Fisking it away will do the trick

Anyhow if that does not work burn another copy its only the blu-rays that are expensive now hehe

I meant disk, my phone auto un-corrected Changed above.

I remember having this problem a couple of years back. The installation kept freezing at Completing Installation... I cleaned my disk, but to no avail.

Then I remember going to a WinPE disk and copying bootmgr from my DVD to the Hard Drive. I think that worked, as far as I can remember. :/

What did you exactly?
Use a Tool that overwrites every sector with 00 oder have you only delete the content of the partition?
If you overwirte all sectors you must possibly only rewrite a new mbr. there are plenty ways to do this.
With a Windows 7 Disk and large hdd's maybe http://support.microsoft.com/kb/927392/en.
You can also use an dos or windows 9x use and create with fdisk an primary partition and then with fdisk /mbr write a new mbr.

Second: use you more than one hdd? If yes disconnect all drives besides boot hdd and install dvd. Sometimes there is a possibility that the hdd boot order from setup would false read and so the bootblock/mbr from win7 setup would be written to the wrong hdd.

Third: have you an EFI Bios? Win8 "cooperates" with the EFI. There is espacially an exclusive mode that makes impossible dualboot. That can also be your problem.

Which, on x64 systems, can be disabled.

myself dosn't have an efi system so that i don't be careful bout this questionable "feature" from Microsoft , but Dusterdoo doesn't say whether he used an x64 or an x86 win8 .
anyway thnx for the info.