All of this has also happened to me.  I was having "IE has stopped working" so often that it was unusable.  I went to Firefox then when I came back and wanted to download IE9 I got the 64 bit version which is not supposed to be the default browser.  I have tried some of your solutions but will try them again.  I still cannot play a video in IE9 because it keeps telling me IE has stoped working. Unfortunately my work website does not recognize Firefox so I must use IE.