Download of PPTX

If I choose open file then the extension is XML and I get a message thet the file is corrupted (see attached picture). If I save it to my computer then everything is fine. Running on Windows Server Standard, 2007, SP2, IIS 7, Net framework 3. Works fine on Localhost but not on this server

the code I use to create the ppt is:
Me.Response.ContentType = "application/vnd.ms-powerpoint"
Me.Response.AppendHeader(“Content-Disposition”, “attachment; filename=” & checkFileNameForIllegalCharacters(Session(“Questionnaire”)) & “.pptx”)
Me.Response.Flush()
Dim st As System.IO.Stream = Me.Response.OutputStream
PPTReport.Write(st)
Me.Response.End()

Hi Bo Ander,

I have tried to understand the issue shared by you but have not been able to clearly understand the issue. It will be really appreciable if you may please share the project code that you are using on your end to reproduce the issue. Please also elaborate the issue further as well. Moreover, as per sample code snippet that you have shared I like to comment that Aspose.Slides for .NET Presenation class is unable to read or write to XML or PPTX format. If this is the case on your end then this might be the issue that you are experiencing.

Thanks and Regards,

Just noticed that the problem occurs with Firefox, works with Explorer and Chrome so it’s some setting in Firefox?