Event ID 4100 appears repeatedly in Event Viewer on Windows 2000 Professional or on Windows Server 2003

On a Microsoft Windows 2000 Professional-based or Windows Server 2003-based computer, the following information about event ID 4100 may appear one to two times a day in Event Viewer:

To resolve this behavior, use the Regsvr32 tool to unregister the Mobsync.dll file from the server:

1. Click Start, click Programs, click Accessories, and then click Command Prompt.
2. Type the following line, and then press ENTER:
   regsvr32 "%systemroot%\system32\mobsync.dll" /u
3. Quit Command Prompt.

After you unregister Mobsync.dll, Client Side Caching (CSC) no longer works. The behavior described in the "Symptoms" section of this article does not affect CSC functionality, but unregistering Mobsync.dll does.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

If you upgrade a workstation that is experiencing this problem to Microsoft Windows XP, you see event ID 4356 on that workstation.

For more information about using Regsvr32, click the following article number to view the article in the Microsoft Knowledge Base: