FIXMBR > Do I or Dont' I?

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Guest

This is a new thread, but based on an old one (<can't get xp to boot after
fix via recovery console>).

After trying just about everything else (such as bootcfg /rebuild, chkdsk,
etc.) to get Windows XP SP2 to boot, I'm at the point of running FIXMBR in
the Recovery console.

However, when I type in FIXMBR and hit the return key, I get this warning:

**caution**
This computer appears to have a non-standard or invalid master boot record.
FIXMBR may damage your partition tables if you proceed.
This could cause all the partitions on the current hard disk to become
inaccesible.
If you are not having problems accessing your drive to not continue.
Are you sure you want to write a new MBR?

I typed <n>. And my system remains unbootable. Microsoft's article
<Restoring the MBR> explains that if a virus caused the problem, AND a
third-party OS has been installed, FIXMBR will damage the partition.

MY QUESTIONS: Is there a way to scan for a virus using the recovery
console? Is there a DOS based program I could run to see if some virus did
this? Does anyone know which virus(es) has this result?

And finally: FIXMBR > Do I or Don't I?
 
Using the Recovery Console to Replace the MBR
You can use the fixmbr command in Recovery Console to rewrite the MBR to
resolve a corrupted MBR on a startup disk. However, running fixmbr
overwrites only the master boot code, leaving the existing partition table
intact. If the corruption in the MBR affects the partition table, running
fixmbr might not resolve the problem.

Caution

Use this command with care because it can damage your partition table if any
of the following apply:
A virus is present and a third-party operating system is installed on the
same computer.
A nonstandard MBR is installed by a third-party disk utility.
A hardware problem exists.
It is recommended that you run antivirus software before you use the fixmbr
command.

Read the full text here:
http://www.microsoft.com/resources/...Windows/XP/all/reskit/en-us/prkd_tro_ldau.asp


steve
 
Hans W said:
This is a new thread, but based on an old one (<can't get xp to boot
after
fix via recovery console>).

After trying just about everything else (such as bootcfg /rebuild,
chkdsk,
etc.) to get Windows XP SP2 to boot, I'm at the point of running
FIXMBR in
the Recovery console.

However, when I type in FIXMBR and hit the return key, I get this
warning:

**caution**
This computer appears to have a non-standard or invalid master boot
record.
FIXMBR may damage your partition tables if you proceed.
This could cause all the partitions on the current hard disk to become
inaccesible.
If you are not having problems accessing your drive to not continue.
Are you sure you want to write a new MBR?

I typed <n>. And my system remains unbootable. Microsoft's article
<Restoring the MBR> explains that if a virus caused the problem, AND
a
third-party OS has been installed, FIXMBR will damage the partition.

MY QUESTIONS: Is there a way to scan for a virus using the recovery
console? Is there a DOS based program I could run to see if some
virus did
this? Does anyone know which virus(es) has this result?

And finally: FIXMBR > Do I or Don't I?
Click to expand...


The first 460 bytes of the MBR (master boot record, which is the first
physical sector on the hard disk and not within any partition) are for
the boot program. That is what FIXMBR (or "FDISK /MBR" for Windows
9x/ME) will replace. It does not move or alter the partition table.
However, a virus can relocate the partition table into a different
location or offset within the first sector or even relocate it past the
first sector and into the rest of the first track. Some boot managers
also do this: they replace the boot program and use a larger partition
table in the extended MBR area in the first track to give them more
options, a larger partition table, so they can manage more than just 4
primary partitions for booting an OS. FIXMBR simply replaces the boot
program. The standard boot program assumes the partition table starts
at its standard offset within the MBR. If a virus or boot manager moved
the partition table, the standard boot program won't know about it. The
result is that you can't boot because the standard boot program cannot
read the partition table. It only reads the partition table but
because of the problem, you might end up taking other actions that
attempt to rewrite or fix the partition table but result in losing the
partitioning information in the relocated partition table.

The warning is just that. If you replace the current boot program with
the standard one, the standard one won't know about relocation of the
partition table. Some boot managers only use a small stub of code in
the 460-byte area to then run the rest of its program in the extended
MBR (so it can run a program larger than 460 bytes). There are
utilities around that will let you backup the 460-byte boot program onto
a floppy (so you could restore them). Google for "MBR backup"; for
example, http://www.diydatarecovery.nl/mbrtool.htm is such a utility.
So you could backup the current boot program, run FIXMBR, and restore
the original boot program if FIXMBR didn't work.

To check for viruses, there are scanners you can run from floppy, like
Stinger from McAfee (http://vil.nai.com/vil/stinger/). The
alt.comp.[anti-]virus groups would have more info on bootable media from
which you can run anti-virus programs.
 
ptdd said:
I suggest you use Partition Table Doctor to fix mbr.
Click to expand...

Why? The recovery console is perfectly able to do this. The message the OP
was getting is the standard message that appears when the MBR is wrong! If
he'd clicked "Yes" instead of "no" all would be right now.
 
Hans W said:
This is a new thread, but based on an old one (<can't get xp to boot
after fix via recovery console>).

After trying just about everything else (such as bootcfg /rebuild,
chkdsk, etc.) to get Windows XP SP2 to boot, I'm at the point of
running FIXMBR in the Recovery console.

However, when I type in FIXMBR and hit the return key, I get this
warning:

**caution**
This computer appears to have a non-standard or invalid master boot
record. FIXMBR may damage your partition tables if you proceed.
This could cause all the partitions on the current hard disk to become
inaccesible.
If you are not having problems accessing your drive to not continue.
Are you sure you want to write a new MBR?
Click to expand...


That's the standard message when the MBR needs fixing! Hit "yes" and you'll
be all ok.
I've done it many times.
 
I clicked yes to the FIXMBR prompt. There was a brief message that the
Master Boot Record had been rewritten. Then I typed exit to get out of the
Recovery Console. Alas, Windows still did not boot.

Instead, it makes like it wants to boot: "Start Windows Normally" is the
default option, then the safe mode options, as well as the "Last Good
Configuration" option. No matter which option I choose, however, it goes
through the initialization screen again, and then back to the screen with
start Windows options. Since the "Start Windows Normally" option
automatically goes after 30 seconds, I find that the boot sequence will
happily loop between these two screens indefinitely, until I intervene with
an attempt to start-up from my XP CDROM and the Recovery Console.

Other than the REcovery Console, I'm also able to press delete key and get
to a setup screen. There I checked my BIOS settings, which seem okay but
what the hell do I know?

Any other great ideas? Or is it reformat time?

Note: In Recovery Console, I can see a list of all of the directories and
files using DIR. But if I attempt CHDIR c:\"program files" (for instance) I
get the message, Access Is Denied. Similarly, if I try to copy a file from
My Documents to my floppy drive, I get Access Is Denied.

Thanks to anyone who's still hangin' with this thread.

Hans W
 
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