esta resposta pode ajudar
Option Strict On
Imports Microsoft.Win32
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Me.CenterToScreen()
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim rk As RegistryKey = Registry.ClassesRoot.OpenSubKey("skype\shell\open\command",
False) '"skype\shell\open\command"
Dim ReturnedValue As String = ""
Try
ReturnedValue = CStr(rk.GetValue(""))
Dim ReturnedValueSplit() As String = ReturnedValue.Split(CChar(ChrW(34)))
ReturnedValue = ReturnedValueSplit(1)
ReturnedValue = ReturnedValue.Replace(CChar(ChrW(34)), "")
If My.Computer.FileSystem.FileExists(ReturnedValue) = False Then
Process.Start("http://www.skype.com/en/download-skype/skype-for-
windows/downloading/")
Else
Process.Start(ReturnedValue)
End If
Catch ex As Exception
End Try
End Sub
End Class