When a user starts Word manually, they activate the instance of Word that you previously created using CreateObject, instead of opening a new instance

Article contributed by Dave Rado

If you start an instance of Word using CreateObject, and don't make it visible, and if a user subsequently starts Word manually, they will activate the instance of Word you created programmatically, instead of opening a new instance. However, if you make Word visible immediately after creating the object, you don't get the problem.

The workaround (assuming you don't want to make Word visible) is to create a temporary Word object, then create the real one, then close the temporary object. This is also covered in Microsoft Knowledge Base article Q188546, which includes the following code sample:

Private Sub CreateWordObject()

Dim TempApp As Word.Application, wrdApp As Word.Application

'Test if object is already created before calling CreateObject:
If TypeName(wrdApp) <> "Application" Then
    'Create temporary Word object
    Set TempApp = CreateObject("Word.Application")
    'Create "real" Word object
    Set wrdApp = CreateObject("Word.Application")
    'Close  temporary Word object   
    Set TempApp = Nothing
End If

End Sub