Linux: Another Way to Restart a Frozen System

When Ctrl + Alt + Backspace does not work, try the following magic command instead of holding the power button.

1. Hold down Alt + Print Screen
2. Type in: reisub
3. The computer should reboot now

Explanation:
r: switches the keyboard from raw mode
e: sends the SIGTERM signal to all processes except init
i: sends the SIGKILL signal to all processes except init
s: attempts to sync all mounted filesystems
u: attempts to remount all mounted filesystems in read-only mode
b: immediately reboots the system, without unmounting partitions or syncing

Ref: Magic SysRq key - Wikipedia