When I try to open MS Office files on my website I first get a popup that says "The website you want to view requests identification. Please choose a certificate" I have "Ignore Client Certificates" checked, and the only other answer I've seen involves playing with the registry which I'd like to avoid.
Even more annoyingly, if I click OK or Cancel in the popup, it then continues on and opens a blank page/spreadsheet/whatever. I know the files aren't corrupted cuz I can download and then open them perfectly through firefox/chrome, and non-MS Office files open fine everywhere.
Neither of these issues occur on my local computer, so I'm assuming it's a setting and/or SSL problem. Displaying files is something I use all over my site, so this is a major bug for me.