Corupted MBR

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Corupted MBR

Postby Bret » Mon Aug 12, 2013 10:11 am

I have an HP laptop with BootIt NG installed. I dual-boot to Win 7 and DOS, but there \re also some options in the menu for the HP Recovery and Tools partitions, which I rarely use.

Last Friday, the machine wouldn't boot at all, saying no OS was installed on the hard drive. After some gyrations (and at first thinking my hard drive was toast), I finally managed to boot DOS and saw that the partition records in the MBR (sector 0) were all set to 0 (no partitions defined at all). It looked like the code in the first part of the MBR was OK, and the AA55h signature was also present. I can also see some data regarding partition names and such in sectors 1-8 (including the "EMBR" signature in the first four bytes of sector 1), so I think the only thing that might have happened was the partition records in sector 0 somehow got erased. I wasn't trying to install a new OS or anything like that -- the MBR just got corrupted for some unknown reason.

I'm able to boot from BootIt NG (v 1.87) via a USB flash drive, but the only thing I can actually get to boot is the DOS partition. According to the manual, if things get "corrupted" somehow (like the MBR getting overwritten by a new OS installation), and BootIt was already installed when you boot from an external device (such as a flash drive), the Floppy Boot Menu should appear and ask if you want to reactivate BootIt. That isn't happening for me.

When I boot from the flash drive, I get a sort of standard-looking BootIt menu, somewhat similar to the one I had when everything was working OK, but with "HD1" at the end of each selection. E.g., the first selection is "Windows 7 HD1". Unfortunately, the only partition that actually boots correctly is DOS, and after I booted that for the first time from the flash drive, the MBR was "fixed" and booting from the hard drive now always boots straight to DOS (no BootIt menu selection any more, unless I boot with the flash drive).

I want to get things back the way they were with as little pain as possible. It looks like the old BootIt configuration information is stored on the hard drive (based on what I see in sectors 1-8), so I think I just somehow need to reactivate BootIt. What I was thinking of doing was something like an "FDISK /MBR" from DOS to overwrite the existing MBR, which will make BootIt think a new OS was installed, and hopefully allow me to reactive it. I'm a little afraid to do that, though, since it may make things worse instead of better.

Any other ideas? Maybe a "backdoor" way to reactivate BootIt? Any details on how BootIt recognizes if it's already installed (why it doesn't think it's already installed on my laptop even though it is)?

Any help would be appreciated.
Bret
 
Posts: 3
Joined: Mon Aug 12, 2013 9:27 am

Re: Corupted MBR

Postby TeraByte Support » Mon Aug 12, 2013 2:49 pm

boot from a bootit ng cd or floppy and you should see the reactivate option
or upgrade to BootIt Bare Metal.


"Bret" wrote in message news:6058@public.bootitng...

I have an HP laptop with BootIt NG installed. I dual-boot to Win 7 and DOS,
but there \re also some options in the menu for the HP Recovery and Tools
partitions, which I rarely use.

Last Friday, the machine wouldn't boot at all, saying no OS was installed on
the hard drive. After some gyrations (and at first thinking my hard drive
was toast), I finally managed to boot DOS and saw that the partition records
in the MBR (sector 0) were all set to 0 (no partitions defined at all). It
looked like the code in the first part of the MBR was OK, and the AA55h
signature was also present. I can also see some data regarding partition
names and such in sectors 1-8 (including the "EMBR" signature in the first
four bytes of sector 1), so I think the only thing that might have happened
was the partition records in sector 0 somehow got erased. I wasn't trying
to install a new OS or anything like that -- the MBR just got corrupted for
some unknown reason.

I'm able to boot from BootIt NG (v 1.87) via a USB flash drive, but the only
thing I can actually get to boot is the DOS partition. According to the
manual, if things get "corrupted" somehow (like the MBR getting overwritten
by a new OS installation), and BootIt was already installed when you boot
from an external device (such as a flash drive), the Floppy Boot Menu should
appear and ask if you want to reactivate BootIt. That isn't happening for
me.

When I boot from the flash drive, I get a sort of standard-looking BootIt
menu, somewhat similar to the one I had when everything was working OK, but
with "HD1" at the end of each selection. E.g., the first selection is
"Windows 7 HD1". Unfortunately, the only partition that actually boots
correctly is DOS, and after I booted that for the first time from the flash
drive, the MBR was "fixed" and booting from the hard drive now always boots
straight to DOS (no BootIt menu selection any more, unless I boot with the
flash drive).

I want to get things back the way they were with as little pain as possible.
It looks like the old BootIt configuration information is stored on the hard
drive (based on what I see in sectors 1-8), so I think I just somehow need
to reactivate BootIt. What I was thinking of doing was something like an
"FDISK /MBR" from DOS to overwrite the existing MBR, which will make BootIt
think a new OS was installed, and hopefully allow me to reactive it. I'm
a little afraid to do that, though, since it may make things worse instead
of better.

Any other ideas? Maybe a "backdoor" way to reactivate BootIt? Any details
on how BootIt recognizes if it's already installed (why it doesn't think
it's already installed on my laptop even though it is)?

Any help would be appreciated.

TeraByte Support
 
Posts: 2334
Joined: Thu May 05, 2011 3:37 pm

Re: Corupted MBR

Postby Bret » Mon Aug 12, 2013 3:29 pm

Booting from a flash drive doesn't work, it has to be a floppy or CD? That's not what the documentation says.
Bret
 
Posts: 3
Joined: Mon Aug 12, 2013 9:27 am

Re: Corupted MBR

Postby TeraByte Support » Mon Aug 12, 2013 10:10 pm

depends on how your BIOS is treating the UFD. If you boot from a floppy or
CD then the BIOS has no choice. Or as I said, you could upgrade.

"Bret" wrote in message news:6061@public.bootitng...

Booting from a flash drive doesn't work, it has to be a floppy or CD?
That's not what the documentation says.

TeraByte Support
 
Posts: 2334
Joined: Thu May 05, 2011 3:37 pm

Re: Corupted MBR

Postby Bret » Tue Aug 13, 2013 9:41 am

I managed to get it fixed. For some reason the laptop wouldn't boot from a USB floppy, but I did manage to make a bootable CD with BING on it and finally got the Floppy Boot Menu like I was supposed to and was able to reactivate. Windows 7 still wouldn't boot after that, and I had to get in and edit the BCD settings. All of the boot related items (Device and OS Device) had been erased (they were reading "HD: unknown"). I still have no idea how everything got corrupted like that.
Bret
 
Posts: 3
Joined: Mon Aug 12, 2013 9:27 am


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