Private Function formIsLoaded(formName As String) As Boolean
  Dim loop As Form

  For Each loop In Forms
    If loop.Name = formName Then
      formIsLoaded = True
      Exit Function
    End If
  Next

  formIsLoaded = False
End Function

This function returns True if the specified form is open in form view or datasheet view.

formIsLoaded(String) As Boolean

form

Visual Basic