Installing Internet Information Services Can Cause Problems in Windows XP

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Article ID: 811412 - View products that this article applies to.
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After you install the FTP service or you add the Microsoft Internet Information Services (IIS) component in Windows XP, you may receive a "C000021A" error message on a blue screen before you log on.


This problem may occur if your computer name contains the word "system", for example, "Mysystem" or "System 32". In the setup process or IIS component, IIS Setup removes the IUSER account's permission on critical system files. Because of a string compare problem, it wrongly removes the system account's ACL on system files so you cannot start the computer.


Service pack information

To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

The English version of this hotfix has the file attributes (or later) 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.
   File name

The Iis.dll file fixes the problem proactively. However, if you receive a "C000021A" error message, and you cannot restart your computer, move the drive to another NTFS operating system, reassign the system - full control permission for files that are in the system32 folder, and then restart the original Windows XP operating system.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows XP Service Pack 2.


To work around this problem, change the computer name.


Article ID: 811412 - Last Review: January 12, 2015 - Revision: 4.6
  • Microsoft Windows XP Professional
  • Microsoft Windows XP Professional SP1
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