On Windows 10 Pro : we can't lunch new instances of Firefox when Firefox was started by Logon Batch Script at startup with GPO - Configuration : Windows 10 Pro + Firefox 67.0.2 (64Bits) (default browser Firefox) - Windows 2016 Server with Active Diretory domain - GPO with Logon Batch Script With command : start http://portail.artzainak.fr After the logon script : firefox is open : OK BUT : we can't start new instances of Firefox : Open a new Windows of Firefox is not working / open shortcut with an URL is not working. No error message, just firefox didn't want to start new windows or open shortcut URL . We need to close Firefox started by logon script before to be able to lunch new Firefox Windows. After we close Firefox started by logon script all work fine. We have this issue on all the computer inn this configuration : Windows 10 Pro + Firefox 67.0.2 (64Bits) + Logon Batch Script who start Firefox with the command start http://portail.artzainak.fr No problem on Windows 7 in the same configuraiton. Have you got a solution?