Weird problem sending a Word doc/Adobe PDF to client

[Strange Cat]

Hello everyone!

I have an app that does some reports (using the included .NET version of
Crystal Reports), (almost) everything is ok.

If the app is installed on some server boxes (looks like is on Windows 2000
server boxes only) the client instead of displaying the correct report is
presented with the login page! (I use windowsforms authentication), this is
VERY weird! If the user puts the login info the report IS NOT displayed...

Looks like it is an authorization problem... what I don't understand is why
the problem occurs only on Win2000 boxes (all of them are members of
domains, i dunno if it matters...).

I use non-persistent cookies (insession).

This is the code-fragment I use to send the report to the clients:
-----------------------------------------------------------------
ExpOpt = Report.ExportOptions
With ExpOpt
.DestinationOptions = DskOpt
.ExportDestinationType = ExportDestinationType.DiskFile
.ExportFormatType = ExportFormatType.WordForWindows
End With

Report.Export()

With Response
.ClearContent()
.ClearHeaders()
.ContentType = "application/msword"
.WriteFile(FTemp)
.Flush()
.Close()
End With

System.IO.File.Delete(FTemp)