Cannot Remove File Association in File Types Dialog Box

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Article ID: 166320 - View products that this article applies to.
This article was previously published under Q166320
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If you create a file association between a program and a file extension, you may then be unable to view, edit, or remove the file association from the File Types dialog box listing of registered file types.


File associations that are created without a description for the file type are not listed as a registered file type, even though they do function properly.


To change the association of a file type that does not appear in the Registered File Types list, follow these steps:
  1. In My Computer or Windows Explorer, press and hold down the SHIFT key while you click a file of the appropriate type with the right mouse button.
  2. On the menu that appears, click Open With.
  3. If you are prompted to, enter a description for the file type. In the "Choose the program you want to use" box, click the program you want to use for this file type.
  4. If the "Always use this program to open this file" check box is not selected, click the check box to select it.
  5. Click the OK button.


Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

For additional information, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: 129050
TITLE : Err Msg: The Extension '.<ext>' Is Already In Use By File...


Article ID: 166320 - Last Review: February 27, 2007 - Revision: 2.2
  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Workstation 4.0 Developer Edition
kbenv kbui KB166320

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