Response.write problem in windows7.

Hi.

I am making Download Page.

And Code is located below

Problem is that it is ok in windows xp but popup a windows for 1 second and close in windows 7.

what's the problem?

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Public Sub executeFile()

Dim fileName  as String = "test.pdf"
Dim fileExten As String = ""
Dim ContentType As String = ""
Dim AddHeader As String = "attachment; filename={0}"
Dim filePath As String = "../Education_AttrFile/{0}"
'Dim filePath As String = ConfigurationSettings.AppSettings("FILEPATH").ToString() + "{0}"

fileExten = fileName.Substring(InStrRev(fileName, ".")) 
AddHeader = String.Format(AddHeader, fileName)
filePath = String.Format(filePath, fileName)

fileExten = fileExten.ToLower()

'contentType를 결정
If fileExten.Equals("txt") = True Then
ContentType = "text/plain"
ElseIf fileExten.Equals("doc") = True Then
ContentType = "Application/msword"
ElseIf fileExten.Equals("xls") = True Then
ContentType = "Application/x-msexcel"
ElseIf fileExten.Equals("pdf") = True Then
ContentType = "application/pdf"
ElseIf fileExten.Equals("jpg") = True Or fileExten.Equals("jpeg") = True Then
ContentType = "image/jpeg"
ElseIf fileExten.Equals("gif") = True Then
ContentType = "image/GIF"
ElseIf fileExten.Equals("png") = True Then
ContentType = "image/png"
End If

Response.Buffer = False
Response.Clear()
Response.ClearContent()
Response.ClearHeaders()
Response.ContentType = ContentType
Response.AddHeader("Content-Disposition", AddHeader)
Response.WriteFile(filePath)
Response.End()

End Sub 'Public Sub executeFile(ByVal fileName As String)