کپی فایل با پنجره کپی

سلام
من با کد زیر کپی فایل رو انجام میدم اما یک اشکالی توش دارم
اینکه وقتی کپی شروع میشه، تا وقتی تموم نشه یا کپی رو کنسل نکنی،برنامه قفل میکنه

Option Explicit

Const FO_COPY = &H2

Const FO_DELETE = &H3

Const FO_MOVE = &H1

Const FO_RENAME = &H4

Const FOF_ALLOWUNDO = &H40

Const FOF_SILENT = &H4

Const FOF_NOCONFIRMATION = &H10

Const FOF_RENAMEONCOLLISION = &H8

Const FOF_NOCONFIRMMKDIR = &H200

Const FOF_FILESONLY = &H80



Private Type SHFILEOPSTRUCT

    hwnd      As Long

    wFunc     As Long

    pFrom     As String

    pTo       As String

    fFlags    As Integer

    fAborted  As Boolean

    hNameMaps As Long

    sProgress As String

End Type



Private Declare Function SHFileOperation Lib "shell32.dll" _

    Alias "SHFileOperationA" (lpFileOp As SHFILEOPSTRUCT) As Long

Private Sub cmdFileOp_Click(Index As Integer)

Dim lFileOp  As Long

Dim lresult  As Long

Dim lFlags   As Long

Dim SHFileOp As SHFILEOPSTRUCT



Screen.MousePointer = vbHourglass

Select Case Index

    Case 0

        lFileOp = FO_COPY

    Case 1

        lFileOp = FO_MOVE

    Case 2

        lFileOp = FO_RENAME

    Case 3

        lFileOp = FO_DELETE

End Select



If chkSilent Then lFlags = lFlags Or FOF_SILENT

If chkYesToAll Then lFlags = lFlags Or FOF_NOCONFIRMATION

If chkRename Then lFlags = lFlags Or FOF_RENAMEONCOLLISION

If chkDir Then lFlags = lFlags Or FOF_NOCONFIRMMKDIR

If chkFilesOnly Then lFlags = lFlags Or FOF_FILESONLY

'

' NOTE:  By adding the FOF_ALLOWUNDO flag you can move

' a file to the Recycle Bin instead of deleting it.

'

With SHFileOp

    .wFunc = lFileOp

    .pFrom = txtSource.Text & vbNullChar & vbNullChar

    .pTo = txtDestination & vbNullChar & vbNullChar

    .fFlags = lFlags

End With



lresult = SHFileOperation(SHFileOp)



' If User hit Cancel button while operation is in progress,

' the fAborted parameter will be true

'

Screen.MousePointer = vbDefault

If lresult <> 0 Or SHFileOp.fAborted Then Exit Sub

MsgBox "Operation Complete", vbInformation, "File Operations"



End Sub