Issue with Function

I have a download function that I use to initiate the open/save dialogue.  While it does what it is supposed to, the method of using it is to put the function call in a seperate page.

The issue I am having is, when I try to use some javascript to close the popup window, the code for the window closing get added to the file on download (txt files).  If I take out the javascript nothing extra gets added to the file, but the popped up window also does not close.

Please see this link to see what I mean:
http://www.getmysupport.com/filemanager/

If you click the floppy disk icon and save or open the file, you will see the javascript in the text file.

The function is:
Function DownloadFile( strFile, strDownloadFilename )
     Dim strFilename,objStream,objFilesystem,objFilestream
     Dim intFileLength
     strFilename = strFile
     Response.Buffer = True
     Response.Clear
     Set objStream = Server.CreateObject("ADODB.Stream")
     objStream.Open
     objStream.Type = 1
     Set objFilesystem = Server.CreateObject("Scripting.FileSystemObject")
     if not objFilesystem.FileExists(strFilename) then
          Response.Write("<h1>Error</h1>: " & strFilename & " does not exist<p>")
          Response.End
     end if
     Set objFilestream = objFilesystem.GetFile( strFilename )
     intFilelength = objFilestream.size
     objStream.LoadFromFile( strFilename )
     if err then
          Response.Write("<h1>Error: </h1>" & err.Description & "<p>")
          Response.End
     end if
     if Len( Trim(strDownloadFilename) ) > 0 then
          strDownloadFilename = Trim( strDownloadFilename )
     else
          strDownloadFilename = objFilestream.name
     end if
     Response.AddHeader "Content-Disposition", "attachment; filename=" & strDownloadFilename
     Response.AddHeader "Content-Length", intFilelength
     Response.Charset = "UTF-8"
     for i = 0 to objStream.size
          i = i + 128000
          Response.BinaryWrite(objStream.Read(128000))
          Response.Flush
     next
     Set objFilestream = Nothing
End Function

and the code for the download.asp page is:
strPath = sPath & uPath(0,0) & "\" & fDown(3,0) 'full path to the file, and the filename
Call DownloadFile(strPath,fDown(3,0))
closeWindow()'to close the popped up window