Oh, I believe that somehow - someone not only installed Chrome onto your computer, but they probably set it as the default browser. I had this happen to me a while back, and I had to go to the Microsoft support site, download a quick little app that set everything back to normal. They changed something inside your registry - and good luck finding the correct key to fix - easiest way to fix it is to go to the MS site - search their support docs for Outlook - Chrome (or some combination) and it should get you straight.