Senna,
This is a deficiency (bug) in VFP. You have to delete the ActiveX, move the Class and readd the ActiveX to the class. If the ActiveX has PEMs that's overridden you can temporarily copy/paste it to a third holding form/class while you are doing the moving.
>When I tried to move a class which contain ActiveX Control, from it's library to another by dragging it, I got an Error Message "Object Class Is Invalid for this container".
>Does anyone know why ?