Поиск файлов по папке и подпапкам (поправить код)

Imports System
Imports System.IO
 
Public Class Form1
    Dim Dirs As String()
    Dim files As String()
    Dim cdir As String
    Private Sub Search(ByVal fold As String, ByVal mask As String)
        Try
            files = System.IO.Directory.GetFiles(fold, mask)
            Me.ListBox1.Items.AddRange(files)
            Dirs = System.IO.Directory.GetDirectories(fold, "*", IO.SearchOption.TopDirectoryOnly)
        Catch ex As Exception
        End Try
        If Not Dirs Is Nothing Then
            For Each cdir In Dirs
                Me.Search(cdir, mask)
            Next
        End If
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Search("C:\", "*.png")
    End Sub
End Class

Imports System.Threading
Public Class Form1
    Public Class Param
        Private _Fold As String
        Private _Mask As String
 
        Public Property Fold As String
            Get
                Return _Fold
            End Get
            Set(value As String)
                _Fold = value.ToString
            End Set
        End Property
 
        Public Property Mask As String
            Get
                Return _Mask
            End Get
            Set(value As String)
                _Mask = value.ToString
            End Set
        End Property
    End Class
 
    Private Delegate Sub Add_Range(ByVal T As String)
 
    Private Sub Write_2_lst(ByVal T As String)
        If Not (InvokeRequired) Then
            ListBox1.Items.Add(T)
        Else
            Invoke(New Add_Range(AddressOf Write_2_lst), T)
        End If
    End Sub
 
    Private Sub Search(p As Param)
 
        Dim Dirs() As String
        Dim files() As String
 
        Try
            files = System.IO.Directory.GetFiles(p.Fold, p.Mask)
            For i = 0 To files.Length - 1
                Write_2_lst(files(i))
            Next
        Catch
        End Try
        Try
            Dirs = System.IO.Directory.GetDirectories(p.Fold, "*", IO.SearchOption.TopDirectoryOnly)
            If Not Dirs Is Nothing Then
                For Each cdir In Dirs
 
                    Dim p1 As New Param
 
                    p1.Fold = cdir
                    p1.Mask = p.Mask
                    Search(p1)
 
                Next
            End If
        Catch
        End Try
 
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim p As New Param
        p.Fold = "C:\"
        p.Mask = "*.png"
        Dim th As New Thread(AddressOf Search)
        th.Start(p)
    End Sub
 
End Class