I design websites for a living and have built many. Recently, working on www.skytargets.com, and typing the URL, IE7 warns me: This site wants to run the following add-on: Microsoft Office XP. I have not written anything to ask for that! Where does that come from and how to get rid of it? This happened after I changed the site to use AJAX (Sajax to be more precise), but it does not happen on other sites designed on the same principles! ... So, it is not "written" in javascript: The javascript portion stays on the client, and all requests go to the server, treating everything in PhP. The "body" tag only contains a single division. After first request, the page division is remade into several, each one "updatable" separately without refresh. There is no mention anywhere of need for Microsoft Office. Editor: just Notepad (and FTP).