Hi, one of my users has got a laptop using windows8.1. I migrate her profil from old XP laptop to the new one. Under her session, when I double-click on firefox icon on the desktop, firefox opens correctly. If I do a second time, I have the msg box "firefox is already running...". If I use the shortcut Ctrl-N, it runs nice, a second instance is openning... so "firefox is already running" is true but "but not responding" is false. Under my session, it works fine, each time I double-clik on the icon, it run a new instance ! I verified I have no more multiple profiles and arguments option (like -P -no-remote...) I tried to create a new profil and only copy (or not) main files (places.sqlite, key3.db, signons.sqlite, permissions.sqlite, search.json, cert8.db)... it doesn't solve. Of course I tried to close firefox, reboot the PC, remove parent.lock... perhaps the only trouble is a small black square stays in the read-only attribut of the profil directory. If I unchecked, it come back quickly! I said her to use Ctrl-N but she has got double-click habits ! Have you any solution? Regards Bertrand (bcag2)