''locking this thread as duplicate, please continue at [https://support.mozilla.org/questions/1129724 /questions/1129724]'' I'm using Windows 7 x64. It appears to install properly. When I double click the the icon, nothing happens. When I hold shift whilst trying that, I get the prompt to start in Safe Mode, then it looks like it will open, but then immediately shuts down again. I "processes" in the Task Manager there are no Mozilla/Firefox processes running. I then rebooted the computer. Same results. I emptied the installation folder and rebooted...same results. I uninstalled, rebooted, reinstalled, rebooted. Same results. There was another post related to this, but appeared to be closed so I started this one.