Microsoft KB Archive/822763

= USB CD-ROM drive may have duplicate drive letters =

Article ID: 822763

Article Last Modified on 10/25/2005

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 3
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 3
 * Microsoft Windows 2000 Service Pack 4

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SYMPTOMS
If you start Microsoft Windows 2000 on a computer that has a USB CD-ROM drive attached, the USB CD-ROM drive has two drive letters assigned to it.



CAUSE
This problem occurs because different managers assign drive letters during different parts of the startup sequence.

During startup, the Windows 2000 I/O Manager enumerates all present storage devices and tries to assign drive letters to each volume. Typically, I/O Manager assigns a drive letter by calling the mount manager. The mount manager is responsible for managing volume names.

In some cases, the mount manager cannot assign a drive letter to a device because the device is not yet available. When this occurs, I/O Manager creates the symbolic link for the drive letter itself, and the mount manager is not notified of the assigned drive letter.

When a USB CD-ROM drive is attached to the computer before startup, the I/O Manager might not assign a drive letter to the CD-ROM drive by means of the mount manager because, although the CD-ROM drive has been enumerated, the CD-ROM drive has not yet been started. In this case, I/O Manager assigns the drive letter itself by creating its own symbolic link for the drive letter.

Later in the startup sequence, the mount manager is notified that the USB CD-ROM drive has arrived. The mount manager then assigns another drive letter to the CD-ROM drive because it is unaware that a drive letter was previously assigned by I/O Manager. Therefore, two drive letters are assigned to the same USB CD-ROM drive.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
No prerequisites are required.

Restart requirement
You must restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version            Size    File name --  26-Jun-2003  18:26  5.0.2195.6762      29,712  Mountmgr.sys



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For more information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:

816915 New file naming schema for Microsoft Windows software update packages

Keywords: kbbug kbfix kbkmode kbplugplay kbstoragedev kbqfe kbusb kbwin2000presp5fix kbhotfixserver KB822763

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