The VBIDE can't provide multiple instances of a SingleUse class

This error occurs under one or more of the following conditions:

• A project that is running in the development environment contains a class whose Instancing property is set to SingleUse.
  
  
• A client project has previously created an instance of this SingleUse class.
  
  
• A client (it may be the same client, or another client) attempts to create a second instance of the SingleUse class.

The error occurs because a SingleUse object can only be created once per instance of the component that provides it. (That is, once an ActiveX Exe project is compiled, creating multiple instances of its SingleUse class will run multiple instances of the Exe component.) However, when the project is in the development environment, it is not possible to start a second instance of the project.

This is a restriction on debugging projects that provide SingleUse classes.

Note   The error will occur even if the first client has released its instance of the SingleUse class. This is because a compiled Exe cannot provide a second instance of a SingleUse class, even after the first has been released.

For more information, see "Scalability Through Multiple Processes: SingleUse Objects," in "Building Code Components" in "Creating ActiveX Components" in the Component Tools Guide.