Hello, maybe it's not a good place to write, but I can't find forums related to the problem in MS clumsy support sites. BTW I've been redirected here from support forums.
The problem is: When requesting favicon.ico from microsoft.com in reply "Content-type" header contains "text/html; charset=UTF-8". I really don't understand why this type instead of returning standard "image/x-icon". Have to notice that bing.com shows "correct" behavior. Also you can check wikipedia, ibm, google etc.