Public Class Form1
Dim Abbruch As Boolean
Dim bot As Object
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
bot = CreateObject("wscript.shell")
Do
bot.sendkeys(TextBox1.Text & "{ENTER}")
For t As Integer = 1 To 50
System.Threading.Thread.Sleep(100) '50 * 0.1 sek warten
Application.DoEvents()
If Abbruch Then Exit Do
Next
bot.sendkeys(TextBox2.Text & "{ENTER}")
For t As Integer = 1 To 50
System.Threading.Thread.Sleep(100) '50 * 0.1 sek warten
Application.DoEvents()
If Abbruch Then Exit Do
Next
Loop
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button2.Click
Abbruch = True
End Sub
End Class