Not able to open microsoft office documents(docx,xls etc) from document library in a FBA site in sharepoint 2010

Question

I have a FBA site and I have a document library in it. I had hosted it in my server. My problem is when i try open any MS Office documents from the doc library I am able to easily save it in our computer and I am able to open those documents, but when try to open MS Office documents directly without saving it, I am asked for credentials again?. I had done the following things.

1 - Disabled "Enable Client Integration" in "Authentication Providers" for FBA

2 - Edited the "serverfilesExcelServer.xml" file IN "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\XML" and comment the line below

<?xml version="1.0" encoding="utf-8" ?>

 <!-- Copyright (c) Microsoft Corporation. All rights reserved. -->

   <ServerFiles>
<Mapping FileExtension="odc" RedirectUrlTemplate= "/_layouts/xlviewer.aspx?id=|0" NoGetRedirect="TRUE"/>
<!-- <Mapping FileExtension="xlsx" RedirectUrlTemplate= "/_layouts/xlviewer.aspx?id=|0" NoGetRedirect="TRUE"/> -->
<Mapping FileExtension="xlsb" RedirectUrlTemplate= "/_layouts/xlviewer.aspx?id=|0" NoGetRedirect="TRUE"/>
    </ServerFiles>

Can anyone kindly throw some light on this issue?

I am facing this issue only when accessing the SP site in an office 2010 installed machine.