The Terminal Services Active X control (mstscax.dll) does not match the version of the Client Shell.  What is going on?

The Terminal Services Active X control (mstscax.dll) does not match the version of the Client Shell.
After you apply a Windows XP service pack, the remote desktop session fails
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Article ID : 928055
Last Review : February 8, 2007
Revision : 1.0
SYMPTOMS
After you use Remote Desktop Client Control (Mstscax.dll) to make a remote desktop connection from a Microsoft Windows XP-based computer, the remote desktop session fails. This problem occurs after you apply Windows XP Service Pack 1 (SP1) or Windows XP Service Pack 2 (SP2) on a client computer.

For example, when you try to connect to a Microsoft Windows Storage Server 2003 R2-based computer that has Remote Desktop for Administration installed, you receive the following error message:
Remote Admin Connection
Remote Admin Web Connection ActiveX Control could not be installed. A connection cannot be made without a working installed version of the control. Please contact the server administrator.
The remote desktop connection then fails.
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CAUSE
This problem occurs when the Mstscax.dll file is not reregistered when the Windows XP service pack is applied.
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RESOLUTION
To solve this problem, run the Regsvr32.exe program to reregister the Mstscax.dll file. To do this, click Start, click Run, type regsvr32 %systemroot%\system32\mstscax.dll, and then click OK.

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