Suppress native application from appearing when converting from .doc to PDF

I am using the com interface

    Dim PDFCreator1 As clsPDFCreator
    Set PDFCreator1 = New clsPDFCreator
    With PDFCreator1
        .cPrintFile ("C:\\How Letters Work.doc")
    End With
    Set PDFCreator1 = Nothing


When I run this code the MSWord application flashes up, a dialog box shows how each page in converting and then closes down.

Implementing this solution would turn away our customers.

Is there any way to suppress this step all together?

(Have this step quietly working in the background)