This is a shutdown hang Are you using "Clear history when Firefox closes" to clear any personal data? *Tools > Options > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" > Settings *https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history I see that you have Norton software running. Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that has effect. *http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/ ---- You can check if there is an update for your graphics display driver and check for hardware acceleration related issues. *https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers You can try to disable hardware acceleration in Firefox. *Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" You need to close and restart Firefox after toggling this setting. See also: *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes