Hey everyone,

I'm creating a Sudoku code with Visual Basics 2005 Express. However, an error appears saying the code is on a infinite loop
Code:
 Private Sub Sudoku_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged, TextBox2.TextChanged, TextBox3.TextChanged, TextBox4.TextChanged, TextBox5.TextChanged, TextBox6.TextChanged, TextBox7.TextChanged, TextBox8.TextChanged, TextBox9.TextChanged, TextBox10.TextChanged, TextBox11.TextChanged, TextBox12.TextChanged, TextBox13.TextChanged, TextBox14.TextChanged, TextBox15.TextChanged, TextBox16.TextChanged, TextBox17.TextChanged, TextBox18.TextChanged, TextBox19.TextChanged, TextBox20.TextChanged, TextBox21.TextChanged, TextBox22.TextChanged, TextBox23.TextChanged, TextBox24.TextChanged, TextBox25.TextChanged, TextBox26.TextChanged, TextBox27.TextChanged, TextBox28.TextChanged, TextBox28.TextChanged, TextBox29.TextChanged, TextBox30.TextChanged, TextBox31.TextChanged, TextBox32.TextChanged, TextBox33.TextChanged, TextBox34.TextChanged, TextBox35.TextChanged, TextBox36.TextChanged, TextBox37.TextChanged, TextBox38.TextChanged, TextBox39.TextChanged, TextBox40.TextChanged, TextBox41.TextChanged, TextBox42.TextChanged, TextBox43.TextChanged, TextBox44.TextChanged, TextBox45.TextChanged, TextBox46.TextChanged, TextBox47.TextChanged, TextBox48.TextChanged, TextBox49.TextChanged, TextBox50.TextChanged, TextBox51.TextChanged, TextBox52.TextChanged, TextBox53.TextChanged, TextBox54.TextChanged, TextBox55.TextChanged, TextBox56.TextChanged, TextBox57.TextChanged, TextBox58.TextChanged, TextBox59.TextChanged, TextBox60.TextChanged, TextBox61.TextChanged, TextBox62.TextChanged, TextBox63.TextChanged, TextBox64.TextChanged, TextBox65.TextChanged, TextBox66.TextChanged, TextBox67.TextChanged, TextBox68.TextChanged, TextBox69.TextChanged, TextBox70.TextChanged, TextBox71.TextChanged, TextBox72.TextChanged, TextBox73.TextChanged, TextBox74.TextChanged, TextBox75.TextChanged, TextBox76.TextChanged, TextBox77.TextChanged, TextBox78.TextChanged, TextBox79.TextChanged, TextBox80.TextChanged, TextBox81.TextChanged
        Dim a As Integer
        Dim solfound As Boolean = True
        Dim textbox As TextBox = CType(sender, TextBox)

        If Not SolutionShwn Then
            If textbox.Text = "" Then
                textbox.Text = "1"
            ElseIf textbox.Text = "9" Then
                textbox.Text = ""
            Else
                textbox.Text = Trim(Str(CInt(textbox.Text) + 1))
            End If
            For a = 1 To 81
                If txtbox(a).Text <> Sudokusolution(a) Then
                    solfound = True
                    Exit For
                End If
            Next a
            congrats.Visible = solfound
        End If
    End Sub
The
Code:
textbox.Text = Trim(Str(CInt(textbox.Text) + 1))
Line reports an infinite loop, but I can't seem to fix the problem, any help would be greatly appreciated, thanks.