Registry filter may fail on Windows XP-based Embedded operating system

The Registry Filter is an Embedded-Enabling Feature used to preserve selected registry keys and values on Microsoft Embedded operating systems that use EWF (Enhanced Write Filter) or FBWF (File-Based Write Filter). These two write filters prevent volume or file system updates, respectively, and the Registry Filter is used to allow specific registry settings to "write through" and be preserved even with an enabled write filter. The Registry Filter is especially important when the embedded systems are used in a network Domain.

On the Windows XP-based Microsoft Embedded operating systems in the Applies To section with an enabled write filter and implemented Registry Filter, the Registry Filter may fail to properly preserve registry values. Two specific values supported by Microsoft, the domain secrets key and the TSCALs key may fail to persist which can result in a loss of domain participation or inadvertently running out of Terminal Service CALs. This issue can potentially affect the preservation of user-configured registry keys as well.
A problem in registry management was discovered during Windows Vista testing that was corrected for Windows Vista and later operating systems. Unfortunately this problem was not corrected in Windows XP operating systems which include those operating systems in the Applies To section.
WES 7, POSReady 7, and later Microsoft Embedded products do not encounter this problem; Microsoft recommends migration to one of these system if you are encountering problems with the preservation of registry values when using the Registry Filter component.
The identified problem with registry management is very narrowly focused and is extremely timing dependent, sensitive to high CPU usage, and very difficult to reproduce. It only affected the way that the Registry Filter works on XP-based Embedded systems. 
Note This is a "FAST PUBLISH" article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. See Terms of Use for other considerations.

Article ID: 2720082 - Last Review: 06/04/2012 15:25:00 - Revision: 1.0

Windows XP Embedded, Windows Embedded Standard 2009, Windows Embedded POSReady 2009

  • KB2720082