Okay I assume this is WINDOWS 8 and IE 11, since it's HIGHLY unlike;ly that ANY system still running IE8 (like Win 2000 or XP) would accept the upgrade to IE11.
IE11 is causing a LOT of problems with a LOT of websites because Microsoft made changes to the code right before the final release and they told NO ONE about it. As a result, Facebook and Yahoo to name juts two, aren't recognizing the browser or Plugins like Flash Player.
Until Microsoft gets a fix released, the recommended workaround is to enable Compatibility View for the affected websites: http://windows.microsoft.com/en-us/internet-explorer/use-compatibility-view#ie=ie-11
Its above 10.