Article ID: 249321 - Last Review: October 11, 2007 - Revision: 4.6

Unable to log on if the boot partition drive letter has changed

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SYMPTOMS

After you try to log on to your Windows 2000-based computer by using a valid user name and password, the Loading your personal settings dialog box is displayed, followed by the Saving your settings dialog box. However, the desktop does not appear, and the Welcome to Windows logon screen is displayed again.

Note If the paging file is located on the system or boot partition, you may also receive the following warning message before returning to the "Welcome to Windows" logon screen:

[Limited Virtual Memory]
Your system has no paging file, or the paging file is too small.

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CAUSE

This problem can occur if your Windows 2000 boot partition drive letter does not match the drive letter assigned during the initial Windows 2000 Setup. Windows 2000 maintains a record of drive letters in a registry based database and re-assigns drive letters based on Globally Unique Identifiers (GUID) recorded for each volume. Should the volume GUID change or be duplicated (by hard drive cloning software), the original drive letter may not be re-assigned to the boot volume.

This may also occur if you break a system/boot mirror, and then attempt to boot to the old shadow drive if the original primary drive is missing or inaccessible. This is because the volume GUID for the shadow drive is different than that of the original primary drive and does not get the same drive letter assigned.

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RESOLUTION

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows

Note If the computer is networked but not part of a domain, you may need to map a connection to the machines IPC$ share using that computer's local administrator credentials before being able to attach using Regedit.exe or Regedt32.exe as described below to make changes.

To permit a logon and/or change the boot volume drive letter back to its originally assigned letter, use any of the following methods:

net use \\remote_machine_name\IPC$ /user:administrator *

Use one of the following procedures to facilitate repairs:

Remove any cloned hard disks added to your computer since the time the logon failures occurred, restart your computer, and then try to log on.
If the computer is networked, run Regedit.exe on another computer to open and modify the registry of the computer that is experiencing the logon failure. Use the information in the following Microsoft Knowledge Base article to change the drive letter back to the original letter assigned to the boot partition:
223188 (http://support.microsoft.com/kb/223188/ ) How to restore the system/boot drive letter in Windows
If the computer is networked, run Regedt32.exe or Regedit.exe on another computer to open and modify the registry of the computer that is experiencing the logon failure. Change the following entry to remove the full path to the Userinit.exe entry as follows:

Change from:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\Current Version\Winlogon\Userinit:Reg_SZ:C:\WINNT\system32\userinit.exe
Change to:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\Current Version\Winlogon\Userinit:Reg_SZ:userinit.exe
After you change the preceding registry entry and are able to logon, perform the steps in the following Microsoft Knowledge Base article to re-assign the proper drive letter to your boot partition and reboot:
223188 (http://support.microsoft.com/kb/223188/ ) How to restore the system/boot drive letter in Windows
Create a "fake" Winnt\System32 folder structure on the drive that is suspected as being assigned the original boot partition drive letter, and then expand and copy the Userinit.exe file from the Windows 2000 CD-ROM into the Winnt\System32 folder on that drive.

You can use the Recovery Console to perform this procedure provided the local security policy\security option "Recovery Console: Allow floppy copy and access to all drives and all folders" is enabled. This will permit the following Recovery Console command to work so you can gain unlimited access to all drives and paths: SET allowallpaths = TRUE This can be implemented as a policy on a domain controller to be applied to the local computer by using the information contained in the following Microsoft Knowledge Base article:
235364 (http://support.microsoft.com/kb/235364/ ) Description of the SET Command in Recovery Console
After you perform the preceding procedure and you are able to log on, perform the steps in the following Microsoft Knowledge Base article to re-assign the proper drive letter to your boot partition and reboot:
223188 (http://support.microsoft.com/kb/223188/ ) How to restore the system/boot drive letter in Windows
With only the system/boot drive in the system, or powered on, boot to a DOS or Windows 9X Start-up diskette that contains fdisk.exe and run the following command:
FDISK /MBR
This re-writes the Master Boot Record and erase the disk signature associated with volume GUID. Windows 2000 should assign default drive letters and allow you logon. Click the article number below for more information about FDISK:
69013 (http://support.microsoft.com/kb/69013/ ) FDISK /MBR rewrites the Master Boot Record