When you search for files that contain text by using the A word or phrase in the file search criterion, the search results may not contain files that contain the text that you specified. For example, .log, .dll, .js, .asp, .xml, .xsl, .hta, .css, .wsh, .cpp, .c, or .h files, or files with no file name extension, may not appear in the search results even if the files contain the text that you specified. This problem may occur even if you specified the file name or type in the All or part of the file name box.

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A filter component is not registered for the file type that contains the text that you specified, or the filter component ignored the text that you specified. For a file type to be included in the search results when you use the A word or phrase in the file search criterion, a valid filter component must be registered for that file type. Windows XP registers filter components only for file types that are associated with common document types. The standard filter components in Windows XP include:

•	Mimefilt.dll: Filters Multipurpose Internet Mail Extension (MIME) files
•	Nlhtml.dll: Filters HTML 3.0 or earlier files
•	Offfilt.dll: Filters Microsoft Office files (Microsoft Word, Microsoft Excel, and Microsoft PowerPoint)
•	Query.dll: Filters plain text files (default filter) and binary files (null filter)

Filter components may ignore some text because of the format or content of the text. For example, the HTML 3.0 filter (Nlhtml.dll) ignores text that is contained in comments in an HTML file (for example, a file with an .htm or .asp extension) because the text is not displayed when you open the file in a browser.

In Microsoft Windows 2000 and earlier versions of Windows, all files are searched for the content that you specify. Windows XP does not search all file to enhance the performance of searching and to avoid extraneous results. This behavior occurs whether or not you use the Indexing service when you search.

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Method 1

To resolve this problem for the following types, obtain the latest service pack for Windows XP or install the "Windows XP Application Compatibility Update, October 25, 2001" from the Windows Update Web site. For more information about this update, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to obtain the latest service pack for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: To resolve this problem for other file types, install a program that registers a filter for the file type that you want to search. If no program that provides a filter is available, you can use the plain text filter for a file type. To do this, add a PersistentHandler key under the file type key in HKEY_CLASSES_ROOT and set its (Default) string value name to the following value: 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:
For example, to use the text filter provider for .zzz files, the following registry setting should exist: After you add this value to the registry, you must log off and then log back on to make the change take effect.

NOTES:

•	The plain text filter may not work for all file types. If adding the plain text filter for the file type does not work, contact the vendor of the file type for availability of a filter for that file type.
•	The HTML 3.0 filter (Nlhtml.dll) ignores text that is contained in comments in an HTML file (for example, a file with an .htm or .asp extension). To search for text that is contained in comments in HTML files, use the plain text filter or the method that is described in method 2.

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Method 2

To configure Windows XP to search all files no matter what the file type, obtain the latest service pack for Windows XP and then turn on the Index file types with unknown extensions option.

If you use this method, Windows XP searches all file types for the text that you specify. This can affect the performance of the search functionality. To do this:

1.	Click Start, and then click Search (or point to Search, and then click For Files or Folders).
2.	Click Change preferences, and then click With Indexing Service (for faster local searches).
3.	Click Change Indexing Service Settings (Advanced). Note that you do not have to turn on the Index service.
4.	On the toolbar, click Show/Hide Console Tree.
5.	In the left pane, right-click Indexing Service on Local Machine, and then click Properties.
6.	On the Generation tab, click to select the Index files with unknown extensions check box, and then click OK.
7.	Close the Indexing Service console.

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:
Network administrators can configure this setting by modifying the registry. To do this, set the FilterFilesWithUnknownExtensions DWORD value to 1 in the following registry key: For more information about how to obtain the latest service pack for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:

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Filter components are included as part of the Indexing service, which is a base service in Windows XP that extracts content from files and constructs an indexed catalog to facilitate efficient and rapid searching. The Indexing service extracts the content by filtering--by using filter components that understand a file's format. A filter component implements the IFilter interface, which supplies methods to read a file to extract text and properties. The Indexing service then merges the extracted information into catalogs of indexes for efficient searches. For additional information about the IFilter interface, visit the following Microsoft Web site:

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