Delete your cache and cookies. Make sure you have the proper url entered. Is there a reason you are running a beta version of Flash 28.b.0 and not the current version : 27.0.0.187 It shows here you are running version 56. It is a unsupported and insecure browser. please update : with Current Release Firefox 57.0 with a Full Version Installer https://www.mozilla.org/firefox/all/ or unfortunately 56.0.2 and below is no longer safe to use for every day use do to secuity issues, but 52.5.0 ESR is. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ <b>Note : Legacy Extensions will be deleted or removed in any version update after May 2018</b>. You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles Please let us know if this solved your issue or if need further assistance.