windows steals MBR every time it boots

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braver · Post by **braver** » Fri Jan 26, 2007 8:15 am

Every time I dual-boot into Windows XP, it steals MBR, so I had to install GRLDR -- Grub for Windows -- which sees my menu.lst. But I have to be alert and catch the boot process. How do I prevent Windows from grabbing MBR back?

slycordinator · Post by **slycordinator** » Fri Jan 26, 2007 8:28 am

braver wrote:Every time I dual-boot into Windows XP, it steals MBR, so I had to install GRLDR -- Grub for Windows -- which sees my menu.lst. But I have to be alert and catch the boot process. How do I prevent Windows from grabbing MBR back?

As part of the installation of windows it writes a windows-compatible mbr, so unless you're gonna rewrite windows' installation program so that when you do a full reinstall that it doesn't clobber the mbr you're gonna have to do something like either reinstalling grub afterwards or using something like GRLDR.

Also, you don't have to be all that alert and catch the boot process. All you do instead is change the default thing that ntldr boots from to booting from GRLDR.

braver · Post by **braver** » Fri Jan 26, 2007 8:57 am

No -- it grabs MBR every time after I boot into windows. That is, instead of GRUB, I get Windows NTLDR. I managed to install GRLDR so I have it, and can indeed make it default. But I don't like Windows to overwrite GRUB every time I *boot* into windows (not install it)! Is it normal?

slycordinator · Post by **slycordinator** » Fri Jan 26, 2007 9:31 am

I've never heard of this happening.

I'm betting there's something more happening. Perhaps you've got grub installed on a disk different than the one that is being booted from so that it's been installed to the mbr of the wrong disk?

Like it's possible that you told grub (when you were in the livecd) to install to (hd0) whereas when you actually boot from disk the real first disk isn't the one that grub was installing to.

I had that happen once.

braver · Post by **braver** » Fri Jan 26, 2007 8:33 pm

The setup is very simple -- I have a laptop, a tablet PC with only the internal drive, /dev/hda. Windows is in the first partition, then there's another partition, a bunch of Linuxen partitions... From any Linuxen I mount the same /boot, and grub is installed by

grub-install /dev/hda

-- after I do that, reboot shows GRUB, but if I ever boot into Windows, they steal the boot, and the next time it's NTLDR!

Rukie · Post by **Rukie** » Sat Jan 27, 2007 5:07 am

I had a similar problem with my computer.
Have you tried going into the grub command prompt
# grub

and then installing it manually into the mbr instead of the boot partiton?
(Or are you already doing that?)

root (hd0)
setup (hd0)

worked for me inside of the grub prompt, rather than using a boot partiton like (hd0,0)

lagalopex · Post by **lagalopex** » Sat Jan 27, 2007 10:01 am

Whats in you grub.conf / menu.lst? What does "fdisk -l /dev/hda" tell you about the active/boot flag?
Are there any "systemtools" or "av-programs" running in windows? Was there any update of windows which could have caused this problem? Is it happening in the "safe-mode" of windows as well?
....

kel_p · Post by **kel_p** » Sun Feb 11, 2007 10:49 pm

slycordinator wrote: I'm betting there's something more happening. Perhaps you've got grub installed on a disk different than the one that is being booted from so that it's been installed to the mbr of the wrong disk?

That's what I'm thinking also..

Also.. you can always bypass the windows bootmanager by making one entry default (normally there is just one), and disabling the counter.

quad · Post by **quad** » Mon Feb 12, 2007 10:03 pm

lagalopex wrote:Are there any "systemtools" or "av-programs" running in windows? Was there any update of windows which could have caused this problem? Is it happening in the "safe-mode" of windows as well?
....

I tend to think that lagalopex is at least partially right, if not fully. Windows itself or antivirus programs may very well check the MBR for any modification from the normal Windows loader. Any inconsistency would be thought of a virus trying to hide itself in the MBR and it would get overwritten any time Windows boots. May as well be one of those vendor-supplied programs doing pretty much the same check to ensure that Windows is still bootable on the notebook. I'd say follow this path and see what you can find.

madisonicus · Post by **madisonicus** » Mon Feb 12, 2007 10:10 pm

I'd like to see your grub.conf if you're still having this problem. I may be behind the times, but I just discovered grub-set-default, and it's magical ability to change the default boot behavior. I have to wonder if this might be part of what's going on.

windows steals MBR every time it boots

windows steals MBR every time it boots

Re: windows steals MBR every time it boots