Error Message "Invalid System Disk" After Setup Reboots
The information in this article applies to:
  a.. Microsoft Windows 95
  b.. Microsoft Windows 98
This article was previously published under Q128730
SYMPTOMS
During the first reboot in Windows Setup, you may receive the following
error message:

Invalid system disk
Replace the disk, and then press any key
You may also receive this error message when you start your computer by
using a Windows Startup disk, or you may receive the following error
message:

This version of Windows does not run on DOS 7.0 or earlier.
CAUSE
This issue can be caused by any of the following conditions:
  a.. Your computer may be infected with a boot-sector virus such as the
AntiCMOS.A virus.
  b.. Your computer is running an anti-virus program.
  c.. Your computer is using hard disk management software (such as Disk
Manager, EZ-Drive, or DrivePro) for hard disk geometry translation. These
tools provide support for large hard disks (more than 1024 cylinders) when
your computer's Basic Input/Output System (BIOS) does not support large hard
disks.
  d.. Windows Setup was unable to copy the system files to the hard disk.
  e.. Security software has disabled access to drive C.
RESOLUTION
Use one of the following methods to correct the problem.
Computer Is Infected with a Virus
Use an anti-virus program to detect and remove the virus, and then reinstall
Windows. Boot-sector viruses infect computers by copying information either
to the boot sector on a floppy disk or the partition table on a hard disk.
During startup, the virus is loaded into memory. Once in memory, the virus
typically infects any non-infected disks that your computer is connected to.
Computer Is Running Anti-Virus Software
Start your computer by using the Windows Startup disk you created during
Windows Setup, and then use the sys command from the Windows Startup disk to
restore the system files to the hard disk.

Some computers use built-in anti-virus software that must be disabled in the
computer's BIOS. For information about how to change settings in the BIOS,
view the computer's documentation or contact the manufacturer of your
computer.
Computer Is Using Disk Management Software
In some cases, Windows may not properly detect that you are using disk
management software and may overwrite the master boot record (MBR)
information. Refer to the documentation for the disk management software you
are using for information about restoring the MBR.

Also, check the Setuplog.txt file for the following statement:

FSLog: BIOS Heads=:64:, BootPart Heads=:64:

The preceding number (64 in this example) may vary from computer to
computer. If these two numbers are different, replace the system files on
your hard disk according to the instructions in the following "Reinstall the
Windows System Files" section. For additional information about how to
determine if your computer is using a drive overlay program, click the
article number below to view the article in the Microsoft Knowledge Base:

186057 How to Tell If Drive Overlay Program Is Installed in Windows


Reinstall the Windows System Files
WARNING: If you are using Disk Manager or any other disk drive overlay
program on a hard disk, make sure that the overlay driver is loaded before
you use the sys command on that hard disk. If the overlay driver is not
loaded and you use the sys command on the hard disk, the drive may not be
recognized as being partitioned by the disk drive overlay program and you
could experience loss of data or an inability to boot from the drive.

Although you can use the sys command with Ontrack Disk Manager and later
versions of MicroHouse EZ-Drive (or EZ-Max) after the overlay driver is
loaded, earlier versions such as EZ-Drive 2.01s require that operating
system files be copied to the overlay installation disk and installed by the
overlay utility. In such cases, the overlay may be damaged if you use the
sys command on the hard disk.
  1.. Start your computer by using the Windows 95 or Windows 98 Startup
disk.
  2.. At the command prompt, type the following commands, pressing ENTER
after each command:
      c:
      cd\windows\command
      attrib c:\msdos.sys -s -h -r
      copy c:\msdos.sys c:\msdos.xxx
      a:
      sys c:
      attrib c:\msdos.sys -s -h -r
      del c:\msdos.sys
      copy c:\msdos.xxx c:\msdos.sys
      attrib c:\msdos.sys +s +h +r


  3.. Remove the Windows Startup disk, and then restart the computer.
Security Software Enabled
Some third-party programs prevent (lock) access to hard disks in your
computer. If this software is installed, contact the manufacturer about how
to remove this software and safely restart Windows 98 Setup. For additional
information about Windows Setup and troubleshooting steps, click the article
number below to view the article in the Microsoft Knowledge Base:

129260 Windows 95 Setup: Description and Troubleshooting Steps

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