Freezes & Crashes
Dealing with system freezes or crashes
Ubuntu does not crash often, but sometimes things can go wrong.....
You can use 'xkill' to kill unresponsive applications. Press 'Alt & F2' then type 'xkill' and press enter.
Now your mouse pointer will look like a 'X' and kill any application you click on.
If ubuntu freezes or crashes, press "Ctrl-Alt-F1"
This will take you to a command line interface (CLI).
Login and then type "top" to launch top, the default CLI task manager.
You can kill any problem process by pressing "k" and then typing in the PID shown on left and pressing enter.
To return to the graphical interface (GUI) press "Ctrl-Alt-F7" or "Ctrl-Alt-F8"
Note - 'htop' is better and easier to use than 'top', it is easily installed using 'sudo apt-get install htop'
If this does not resolve the issue, press "Ctrl-Alt-F1" again,
Login if needed and then type "sudo shutdown -r now" to restart your computer.
You can also use "sudo restart lightdm" to restart the display manager & return to the graphical login screen.