Context: We are running Firefox 31.3.0 ESR on Windows Server 2012 R2 in a Terminal Services environment. We have Firefox as well as other web browsers available on the server to allow users flexibility and for cases where certain sites are less functional for certain browsers. Problem: We have observed that if a user that has not selected a default browser and has not used Firefox on the server yet, when they attempt to launch a link from Outlook 2013 and selects Firefox to launch the link, Firefox will launch but not navigate to the page and the menu button is no longer functional. Additionally, if they launch Firefox on its own it will not navigate to their home page and the menu button continues to be non-functional. Safe Mode does not resolve the issue, nor does refreshing/resetting Firefox, nor does removing the Mozilla folder from the user's application data in their Windows user profile. The only way we have found to resolve this so far is to fully reset the user's Windows profile, which leads me to believe that this is related to something stored within the user's registry settings. Has anyone observed any similar issue in the past? Thanks.