Downloading closes my application

[Steven]

When a user is redirected to our app thru a _blank target hyperlink,
everything seems to work fine until he downloads a file from our site. This
is the code used for downloading:

Dim fso As New Scripting.FileSystemObject()
Dim TS As Object
Dim strFile As String
Dim strFileSave As String
Dim b As Byte
Dim MyFileInfo As FileInfo
Dim StartPos, FileSize As Long
Dim sr As StreamReader

strFile = Application("tmpFolder") & Session("ID") &
Session("Socio") & ".qif"
strFileSave = Session("ID") & Session("Socio") & ".qif"

MyFileInfo = New FileInfo(strFile)
FileSize = MyFileInfo.Length
Response.ContentType = "bad/type"
Response.AddHeader("Content-Disposition", "attachment;filename=" &
strFileSave)
HttpContext.Current.Response.AppendHeader("Content-disposition",
"attachment; filename=" & strFileSave)
HttpContext.Current.Response.WriteFile(Application ("tmpFolder") &
strFileSave, StartPos, FileSize)
HttpContext.Current.Response.End()

Once the download Save As dialog window pops up, our app window closes. The
strange thing is the user can still download the file ok, but has to navigate
to our site again, to start all over.

Any ideas or suggestions?

Thanx