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Q139107: Err Msg: Uninstall Is Unable to Write to the MBR

Article: Q139107
Product(s): Microsoft Windows 95.x Retail Product
Version(s): 95
Operating System(s): 
Keyword(s): win95
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft Windows 95 
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SYMPTOMS
========

When you try to use the Uninstall option in the Add/Remove Programs tool, you
may receive the following error message when your computer restarts:

  Uninstall is unable to write to the MBR

When this occurs, the Uninstall procedure cannot be completed, and you may not be
able to start the computer from the hard disk.

CAUSE
=====

This problem can occur when any of the following conditions exists:

- The hard disk's Master Boot Record (MBR) is damaged.

- A software or hardware-level virus scanning program is protecting the MBR.

- You are using third-party disk partitioning software.

- You computer has been infected with a boot-sector virus.

RESOLUTION
==========

Use the information in the appropriate section below to try to resolve the
problem. If you cannot start your computer from the hard disk, you can start it
using your Windows 95 Startup disk.

MBR Protected by Virus Scanning Software
----------------------------------------

If you suspect that a virus scanning program is preventing Uninstall from writing
to the MBR, disable the virus scanning program by editing the Config.sys or
Autoexec.bat file to temporarily disable the program. Place the word "Rem"
(without the quotation marks) at the beginning of the line or lines used to load
the virus scanningprogram. After you make this change, restart the computer.

For information about the virus scanning program, consult the program's
documentation or manufacturer.

MBR Protected by Hardware-Level Virus Scanning Program
------------------------------------------------------

To disable hardware-level virus detection, run your computer's CMOS configuration
utility and disable the virus detection.

For information about your computer's CMOS configuration utility, please consult
the computer's documentation or manufacturer.

Third-Party Partitioning Software
---------------------------------

If third-party partitioning software is preventing Uninstall from writing to the
MBR, refer to the software's documentation for information about restoring the
previous MBR or modifying the current MBR.

Boot-Sector Virus
-----------------

If you suspect that your computer has been infected with a boot-sector virus, use
an anti-virus program to detect and remove the virus.

For additional information about viruses, please see the following article in the
Microsoft Knowledge Base:

  Q82923 Methods to Detect a Boot-Sector Virus

After you resolve the problem that is preventing Uninstall from writing to the
MBR, start your computer with your Windows 95 Startup disk, and then run
Uninstall by typing the following command at the command prompt

  " <disk>:\uninstal <W95undo.dat_location> " (without the
  quotation marks)

where <disk> is the drive containing the Startup disk and
<W95undo.dat_location> is the full path to the W95undo.dat file.

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Keywords          : win95 
Technology        : kbWin95search kbZNotKeyword3
Version           : 95

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