Hmmm, I've been using Outlook and Firefox together for many years and I always had to close the Firefox window or just switch back to Outlook. Could the arrows have been a feature of an add-on? If that seems like a possibility, you could check to see whether any relevant-looking add-ons have become disabled: orange Firefox button ''or'' classic Tools menu > Add-ons Check both the Extensions category and Plugins category, and make sure to scroll through the entire list in case the name isn't obvious.