prevent osk.exe minimize on kiosk applications

i have a kiosk application in vb.net and i get some problems with the on screen keyboard. When the user clicks the minimize button, the keyboard hides after the form which has the property windowSate = Maximized, so there is no way for the keyboard to appear again before the form unless the application is restarted.

the solution i got is to close the keyboard each time i want to open it, i mean i call the close function and after that i call the open function, so even if the keyboard is hidden somewhere, it will be closed, than i can open it.

the problem is that not always i get results with this way, so i thought the new process gets a different id, and i cant get it.

the functions i use actually are:

 Private Sub CloseKeyboard()
        If Me.oskProcess IsNot Nothing Then
            If Not Me.oskProcess.HasExited Then
                'CloseMainWindow would generally be preferred but the OSK doesn't respond.
                Me.oskProcess.Kill()
            End If
            Me.oskProcess.Close()
            Me.oskProcess = Nothing
        End If
    End Sub
    Private Sub OpenKeyboard()
        Try
            If Me.oskProcess Is Nothing OrElse Me.oskProcess.HasExited Then
                If Me.oskProcess IsNot Nothing AndAlso Me.oskProcess.HasExited Then
                    Me.oskProcess.Close()
                End If
                Me.oskProcess = Process.Start(Application.StartupPath & "\osk.exe")
            End If
        Catch
        End Try
    End Sub

if someone has experienced some similar problem, it would be very helpful telling me how he solved this situation. maybe there is a way to disable the minimize button of the osk, but i think its difficult to manipulate the exe of Windows.
maybe i can find out the id of the osk process and kill exactly that, i don't know why sometimes i get results with the close-open solutions, and sometimes i don't.

thanks a lot for your time