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.
This problem occurs when the Mstscax.dll file is not reregistered when the Windows XP service pack is applied.
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.