Microsoft KB Archive/870544

= Unexpected behavior when you access files on a recordable CD or DVD =

Article ID: 870544

Article Last Modified on 10/30/2004

-

APPLIES TO


 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Server
 * Microsoft Windows NT 4.0
 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Server 4.0 Standard Edition

-





SYMPTOMS
When you access a file on a recordable CD or DVD, on rare occasions, the wrong file is accessed.

For example, when you double-click a file in Windows Explorer to open the file, a different file may open. The different file may have a similar name to the file that you double-clicked and is in the same folder on the CD or on the DVD.



CAUSE
This behavior may occur if all the following conditions are true:
 * Your operating system is one of the following:
 * Microsoft Windows Server 2003
 * Microsoft Windows XP
 * Microsoft Windows 2000
 * Microsoft Windows NT 4.0
 * On a recordable CD or DVD, one or more files in a folder use the same name format that is used to auto-generate short file names.
 * On a recordable CD or DVD, one or more files in a folder have similar file names. For example, a folder might contain the following two files:
 * ThisIsATestFile.jpg
 * ThisIs~1.jpg

Consider the scenario where you have two files with similar names, such as ThisIsATestFile.jpg and ThisIs~1.jpg. If you double-click the ThisIs~1.jpg file in Windows Explorer, the ThisIsATestFile.jpg file may open.

If you copy the ThisIs~1.jpg file to your hard disk, the following two files appear on the hard disk:
 * ThisIs~1.jpg
 * ThisIsATestFile.jpg

However, both files are a copy of the same ThisIsATestFile.jpg file. Because of this behavior, you may not be able to open or to copy some of the files from the folder on the CD or on the DVD to your hard disk. Specifically, you may not be able to open or to copy the files that use short file names.



WORKAROUND
To avoid this behavior, do not use the same file naming format that is used for auto-generated short file names when you save files to a recordable CD or DVD.

To work around this issue, if you have already saved files to a recordable CD or DVD that you can no longer access, follow these steps:
 * 1) Access the recordable CD or DVD by using a computer that is running one of the following operating systems:
 * 2) * Microsoft Windows Millennium Edition
 * 3) * Microsoft Windows 98
 * 4) * Microsoft Windows 95
 * 5) Copy the files to the hard disk of the computer that is running one of these operating systems.
 * 6) Transfer the files from the hard disk of this computer to your computer by using a floppy disk, a network connection, an e-mail message, or a recordable CD or DVD that uses a different file naming convention.



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
An auto-generated short file name has a maximum of eight characters in its name and three characters in its extension. (This format is generally referred to as the 8.3 file name format.) An auto-generated short file name will also have a “~” symbol as either the sixth or the seventh character in the name. A one-digit or a two-digit number appears after that character. (For example, ThisIs~1.jpg and ThisI~14.jpg are auto-generated short file names.) Short file names are auto-generated only for files with names that are longer than 8 characters before the period &quot;.&quot;.

When Windows accesses data files on a CD or a DVD, the CD File System (CDFS) is used. Short file names are assigned to files so that the files can be accessed by programs that can use only the 8.3 file name format. CDFS uses an algorithm to assign the auto-generated short file names. The algorithm makes sure that the files have the same short file names every time that the CD is accessed and that there are never two of the same auto-generated short file names for files in the same folder. However, the algorithm does not make sure that an auto-generated short file name is not a duplicate of a file name that was already saved to the folder. Placement in the file system is one of the criteria that the CDFS algorithm uses to assign short file names. Therefore, you may use different software to save the same files to the same folder to a recordable CD or DVD and still experience the behavior that is mentioned in the &quot;Symptoms&quot; section.

This behavior does not occur when you save a file to a hard disk. When you save a file to a folder on a hard disk, the file system that is used on the hard disk saves auto-generated short file names in the file system to make sure that no duplicate file names exist. With CDFS standards, you cannot save both a long and a short file name to the same file system. Therefore, auto-generated short file names must be assigned when the CDs are read.

