You attempt to use the
dual boot configuration with the installation of an earlier version of Windows operating system and find out that Windows Vista will no longer start and just this earlier version. Or you are installing additional data on Windows XP on a computer that has Windows Vista with Windows XP in a dual boot configuration when an error message pops up saying that “
Disk read error has occurred.” What should you do?
These problems arise because earlier versions of Windows operating systems, such as
Windows XP are not compatible with the startup method of
Windows Vista. Windows Vista uses a new Boot Configuration Database store which has a boot menu and all data on operating systems installed on the computer. Therefore, the
boot.ini file from Windows XP cannot start Windows Vista.
Earlier versions of Windows run on a basic input/output system (BIOS) based computer, wherein the boot process starts with the BIOS system, as seen in Windows XP. This establishes the boot device then loads the first physical sector, named the
master boot record (MBR). The MBR comprises the partition table and the needed boot execution code which finds the boot sector on the active partition from the partition table. When found, it passes the control to it to load the Ntldr program. This program in turn parses the Boot.ini file which is responsible for enumerating the operating systems installed in the computer.
When Windows Vista starts on a computer that is BIOS based, the BIOS loads the MBR and then the boot sector using the new
Windows Boot Manager program (Bootmgr). This Bootmgr parses the binary coded decimal (BCD) Boot.ini file, enumerates the installed operating systems and then displays the boot menu. If there is an earlier version that is configured in a dual boot position, then the Windows Boot Manager program transfers control to the Ntldr program for the earlier version of the Windows operating system, when Windows Vista is selected from the boot menu.
Installing an earlier version of Windows on a computer with Windows Vista will cause Setup to overwrite everything from the MBR, boot sector and boot files, losing its forward compatibility with Windows Vista.
Here are the steps to follow to resolve this problem. 1. Access
Administrator rights before starting to run these procedures in the command prompt. Using
Windows Vista, click on
Start, then
Accessories, then right click on
command prompt shortcut, and then select
Run as Administrator.
2. Use
Bootsect.exe to restore the
Windows Vista MBR and boot code to transfer control to Windows Boot Manager Program by entering “
Drive:\boot\Bootsect.exe/NT60 All” at command prompt, the drive being where the Windows Vista installation media is found.
Use
Bededit.exe to create an entry in the BCD Boot.ini file manually for the earlier Windows operating system version. Type the following commands at command prompt:
Drive:\Windows\system32\Bcdedit /create {ntldr} –d "Description for earlier Windows version"
Drive:\Windows\system32\Bcdedit /set {ntldr} device partition=x:
Drive:\Windows\system32\Bcdedit /set {ntldr} path \ntldr
Drive:\Windows\system32\Bcdedit /displayorder {ntldr} –addlast Note: Drive is the drive where Windows Vista is installed
"Description for earlier Windows version” is any text to describe the early windows version
x: is the drive letter for the active partition 3. Restart the computer.
After the computer reboots, then you can access Windows Vista once again.
How to resolve errors in dual boot configuration 
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