When you try to run an ActiveX DLL from the Visual Basic IDE, you receive the following error message:

When Visual Basic runs an ActiveX DLL from the IDE, it calls the CoRegisterClassObject application programming interface (API) to temporarily register the server. This creates the AppId and specifies it to run in the Interactive User context.

This problem occurs because of a bug in the Microsoft OLE Libraries 4.0, which are included with the Microsoft Platform Software Development Kit (SDK). CoRegisterClassObject fails with the error message that is listed in the "Symptoms" section of this article under the following conditions:

•	If the ActiveX server that calls the API is set to run by using the Interactive User identity. -and-
•	The string that is associated with the following registry key contains any value other than a single valid executable name for the shell process: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon Shell=

Under Microsoft Windows 2000, this error occurs when the Certification Authority service does not start.

Make sure that the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon Shell= registry key contains a single valid executable name for the shell process.

To resolve this problem under Windows 2000, you can install the "Client for Microsoft Network" component and then reboot.

See the "References" section of this article for instructions about how to handle this error when it is related to the Certification Authority on systems that are running Windows 2000.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base: