VB.net Form unexpectingly terminating - vb.net

Question

Hi I have the following form but cant figureout why its upbrubtly terminiating when difrent buttons are clicked?
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
Private Sub button1_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseEnter
Dim TEST1 As Integer = System.IO.Directory.GetFiles("C:\test\test").Length
If TEST1 = 0 Then
Me.WebBrowser1.Navigate("http://www.hotmail.com")
End If
End Sub
Private Sub button1_MouseLeave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseLeave
Me.WebBrowser1.Navigate("http://WWW.facebook.com")
End Sub
Private Sub button2_MouseLeave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.MouseLeave
Me.WebBrowser1.Navigate("http://WWW.facebook.com")
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.WebBrowser1.Navigate("file://C:\test\test")
Button1.Enabled = False
Button2.Enabled = True
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Me.WebBrowser1.Navigate("file://C:\test")
Button2.Enabled = False
Button1.Enabled = True
End Sub
Private Sub button2_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.MouseEnter
Dim TEST2 As Integer = System.IO.Directory.GetFiles("C:\test\test").Length
If TEST2 = 0 Then
Me.WebBrowser1.Navigate("http://www.hotmail.com")
End If
End Sub
The terms face book and hotmail are just random to keep company site private :)

Answer 1

I suspect the Mouse_Enter event and the Mouse_Leave events are not giving time to the webbrowser to fully load the document and maybe it is internally crashing.
Try checking if the webbrowser has finished working before navigating again and tell us:
Use
If WebBrowser1.ReadyState = WebBrowserReadyState.Complete
Me.WebBrowser1.Navigate("http://www.google.com")
End if