preload immagini lato client di fotogallery

[biocco]

ho creato una fotogallery a directory ma quando carco le immagini non le carica tutte e me le visualizza col quadratino ma in realà e perche non fa in tempo! infatti se faccio click destro mouse e mostra immagine appare!!! come faccio a fare un preload automatico lato client ???
grazie a tutti

  Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Inserire qui il codice utente necessario per inizializzare la pagina
        ' Riempie contenuto della directory...
        Dim ListaDirectory() As String
        Dim ListaFiles() As String
        Dim A As Integer
        Dim Hyp As HyperLink
        Dim Img As HyperLink
        Dim lbl As Label
        Dim PathScelto As String
        Dim TmpPath As String
        Dim TmpPathScelto As String
        Dim DirectoryPrincipale_S As String
        Dim DirectoryPrincipale As String
        Dim r As TableRow
        Dim c As TableCell
        Dim Nr As Integer
        Dim NC As Integer
        Dim r1 As New TableRow

        lblHead.Visible = False
        lblTitle.Style("TEXT-ALIGN") = "LEFT"
        lblDirectory.Style("TEXT-ALIGN") = "LEFT"

        Try
            DirectoryPrincipale = "FotoEventi"
            DirectoryPrincipale_S = "FotoEventi_Small"
            PathScelto = Request("PATHSCELTO")
            TmpPathScelto = IIf(PathScelto = "", DirectoryPrincipale_S, PathScelto)
            If PathScelto = "" Then
                PathScelto = Directory.GetParent(Server.MapPath("Fotogallery.aspx")).FullName & "\" & DirectoryPrincipale_S
            Else
                PathScelto = Directory.GetParent(Server.MapPath("Fotogallery.aspx")).FullName & "\" & PathScelto & "\"
                lblTitle.Visible = False
                lblDirectory.Visible = False
                lblHead.Text = "" & Mid(Request("PATHSCELTO"), 18)
                lblHead.Style("TEXT-ALIGN") = "LEFT"
                lblHead.Visible = True
            End If

            ListaDirectory = Directory.GetDirectories(PathScelto)
            For A = LBound(ListaDirectory) To UBound(ListaDirectory)
                TmpPath = TmpPathScelto & "\" & Mid(ListaDirectory(A), InStrRev(ListaDirectory(A), "\") + 1)
                Hyp = New HyperLink
                Hyp.Text = Mid(ListaDirectory(A), InStrRev(ListaDirectory(A), "\") + 1) & "
"
                Hyp.NavigateUrl = "FotoGallery.aspx?PATHSCELTO=" & TmpPath
                lblDirectory.Controls.Add(Hyp)
            Next
            ListaFiles = Directory.GetFiles(PathScelto)
            For A = LBound(ListaFiles) To UBound(ListaFiles)
                Img = New HyperLink
                Img.ImageUrl = Mid(Mid(ListaFiles(A), InStr(ListaFiles(A), DirectoryPrincipale_S) - 1), 2)
                Img.NavigateUrl = Replace(Mid(Replace(Mid(ListaFiles(A), InStr(ListaFiles(A), DirectoryPrincipale_S) - 1), DirectoryPrincipale_S, DirectoryPrincipale), 2), "_s.", ".")
                Img.ToolTip = Mid(ListaFiles(A), InStrRev(ListaFiles(A), "\") + 1)
                If A Mod 4 = 0 Then
                    Nr = Nr + 1
                    r = New TableRow
                    r1 = New TableRow
                End If
                c = New TableCell
                c.Controls.Add(Img)
                c.HorizontalAlign = HorizontalAlign.Center
                r.Cells.Add(c)

                lbl = New Label
                lbl.Text = LCase(Img.ToolTip)
                lbl.Font.Bold = False

                c = New TableCell
                c.Controls.Add(lbl)
                c.HorizontalAlign = HorizontalAlign.Center
                r1.Cells.Add(c)
                Table1.Rows.Add(r)
                Table1.Rows.Add(r1)
            Next
            Exit Sub
        Catch EX As Exception
        End Try

    End Sub